RAB6KIFL/KIF20A epitope peptide and vaccines containing the same

ABSTRACT

The present invention provides oligopeptides comprising the amino acid sequence selected from the group consisting of SEQ ID NOs: 3, 4 and 5. The present invention also provides a pharmaceutical composition containing the amino acid sequence of selected from the group consisting of SEQ ID NOs: 3, 4 and 5 formulated for the treatment or prevention of cancer in a subject. Furthermore, the present invention provides a method of inducing immune response using such oligopeptides and pharmaceutical agents.

PRIORITY

The present application is a U.S. National Stage Application ofPCT/JP2009/005382, filed Oct. 15, 2009, which claims the benefit of U.S.Provisional Application No. 61/197,106, filed on Oct. 22, 2008, theentire contents of which are incorporated by reference herein in theirentirety.

TECHNICAL FIELD

The present invention relates to the field of biological science, morespecifically to the field of cancer therapy. In particular, the presentinvention relates to novel oligopeptides and use thereof.

BACKGROUND ART

It has been demonstrated that CD8 positive CTLs recognize epitopepeptides derived from the tumor-associated antigens (TAAs) found onmajor histocompatibility complex (MHC) class I molecule, and then killthe tumor cells. Since the discovery of the melanoma antigen (MAGE)family as the first example of TAAs, many other TAAs have beendiscovered, primarily through immunological approaches (NPL 1: Boon T,Int J Cancer 1993 May 8, 54(2): 177-80; NPL 2: Boon T & van der BruggenP, J Exp Med 1996 Mar. 1, 183(3): 725-9). Some of the TAAs are nowcurrently undergoing clinical development as immunotherapeutic targets.

Identification of new TAAs, capable of inducing potent and specificanti-tumor immune responses, warrants further development and clinicalapplication of peptide vaccination strategies for various types ofcancer (NPL 3: Harris C C, J Natl Cancer Inst 1996 Oct. 16, 88(20):1442-55; NPL 4: Butterfield L H et al., Cancer Res 1999 Jul. 1, 59(13):3134-42; NPL 5: Vissers J L et al., Cancer Res 1999 Nov. 1, 59(21):5554-9; NPL 6: van der Burg S H et al., J Immunol 1996 May 1, 156(9):3308-14; NPL 7: Tanaka F et al., Cancer Res 1997 Oct. 15, 57(20):4465-8; NPL 8: Fujie T et al., Int J Cancer 1999 Jan. 18, 80(2): 169-72;NPL 9: Kikuchi M et al., Int J Cancer 1999 May 5, 81(3): 459-66; NPL 10:Oiso M et al., Int J Cancer 1999 May 5, 81(3): 387-94). To date, therehave been several reports of clinical trials using thesetumor-associated antigen derived peptides. Unfortunately, only a lowobjective response rate has been observed in these cancer vaccine trialsso far (NPL 11: Belli F et al., J Clin Oncol 2002 Oct. 15, 20(20):4169-80; NPL 12: Coulie P G et al., Immunol Rev 2002 October, 188:33-42; NPL 13: Rosenberg S A et al., Nat Med 2004 September, 10(9):909-15).

Recently, HLA class I-binding peptide sequence can be expected usingalgorithms (NPL 14: Journal of Immunological Methods, (1995), Vol. 185,pp. 181-190, NPL 15: J. Immunol., (1994), Vol. 152, pp. 163-175, NPL 16:protein science, (2000), Vol. 9, pp. 1838-1846). However, it is hard tosay that the expected epitope peptide can be processed naturally in thetarget cells and expressed on the target cell surface with HLA molecule.Moreover, the algorithm, for example BIMAS(http://bimas.dcrt.nih.gov/cgi-bin/molbio/ken_parker_comboform) (NPL 17:Parker K C, et al., (1994) J. Immunol.; 152(1):163-75; NPL 18: KuzushimaK, et al., (2001) Blood; 98(6):1872-81.)) can suggest the HLAmolecule-binding peptide, but the suggested peptide is not so rigorous(NPL 19: Bachinsky M M, et. al., Cancer Immun. 2005 Mar. 22; 5:6.). ThusTAA screening still remains a lot of challenges and difficulties.

Pancreatic cancer has a poor prognosis, with an overall 5-year survivalrate of about 5% (1). A surgical resection remains the only option for along term survival, but patients with resectable pancreatic cancer arein the minority (9-22%) (NPL 20: Sener S F, et al. J Am Coll Surg 1999;189:1-7, NPL 21: Eloubeidi M A, et al. Am J Surg 2006; 192:322-9, NPL22: Goonetilleke K S, et al. Int J Surg 2007; 5:147-51.). Even in thesepatients, however, the 5-year survival rate remains approximately 20% inspite of surgery with a curative intent (NPL 23: Smeenk H G, et al.Langenbecks Arch Surg 2005; 390:94-103, NPL 24: Yeo C J, et al. Ann Surg1995; 221:721-31.). Up to 80% of patients present with locally advancedor metastatic disease, and their median survival ranges from 6 to 9months (NPL 25: Lockhart A C, et al. Gastroenterology 2005;128:1642-54.). Hence, the development of novel therapeutic modalities isan issue of great importance, and immunotherapy may be a potentialtreatment for pancreatic cancer.

RAB6KIFL (KIF20A) was first identified to play a role in the dynamics ofthe Golgi apparatus through direct interaction with Rab6 small GTPase(NPL 26: Echard A, et al. Science 1998; 279:580-5.). RAB6KIFL belongs tothe kinesin superfamily of motor proteins, which have critical functionsin trafficking of molecules and organelles (NPL 26: Echard A, et al.Science 1998; 279:580-5, NPL 27: Hirokawa N, et al. Curr Opin Cell Biol1998; 10:60-73, NPL 28: Allan V J, and Schroer T A. Curr Opin Cell Biol1999; 11:476-82.). Recently, Taniuchi K et al. reported that RAB6KIFLwas overexpressed in pancreatic cancer tissues (NPL 29: Taniuchi K, etal. Cancer Res 2005; 65:105-12.). They found evidence for a criticalrole of RAB6KIFL in pancreatic carcinogenesis.

Through gene expression profile analysis using a genome-wide cDNAmicroarray containing 23,040 genes, RAB6KIFL (KIF20A) was recently shownto be up-regulated in several cancers such as bladder cancer (PTL 1:WO2006/085684), small cell lung cancer (SCLC) (PTL 2: WO2007/013665) andhormone-refractory prostate cancer (HRPC) (PTL 3: WO2008/102906), thedisclosures of which are incorporated by reference herein. Further, someepitope peptides of KIF20A gene products were also identified (PTL 4:WO2008/102557).

CITATION LIST Patent Literature

-   [PTL 1] WO2006/085684-   [PTL 2] WO2007/013665-   [PTL 3] WO2008/102906-   [PTL 4] WO2008/102557

Non Patent Literature

-   [NPL 1] Boon T, Int J Cancer 1993 May 8, 54(2): 177-80-   [NPL 2] Boon T & van der Bruggen P, J Exp Med 1996 Mar. 1, 183(3):    725-9-   [NPL 3] Harris C C, J Natl Cancer Inst 1996 Oct. 16, 88(20): 1442-55-   [NPL 4] Butterfield L H et al., Cancer Res 1999 Jul. 1, 59(13):    3134-42-   [NPL 5] Vissers J L et al., Cancer Res 1999 Nov. 1, 59(21): 5554-9-   [NPL 6] van der Burg S H et al., J Immunol 1996 May 1, 156(9):    3308-14-   [NPL 7] Tanaka F et al., Cancer Res 1997 Oct. 15, 57(20): 4465-8-   [NPL 8] Fujie T et al., Int J Cancer 1999 Jan. 18, 80(2): 169-72-   [NPL 9] Kikuchi M et al., Int J Cancer 1999 May 5, 81(3): 459-66-   [NPL 10] Oiso M et al., Int J Cancer 1999 May 5, 81(3): 387-94-   [NPL 11] Belli F et al., J Clin Oncol 2002 Oct. 15, 20(20): 4169-80-   [NPL 12] Coulie P G et al., Immunol Rev 2002 October, 188: 33-42-   [NPL 13] Rosenberg S A et al., Nat Med 2004 September, 10(9): 909-15-   [NPL 14] Journal of Immunological Methods, (1995), Vol. 185, pp.    181-190-   [NPL 15] J. Immunol., (1994), Vol. 152, pp. 163-175-   [NPL 16] protein science, (2000), Vol. 9, pp. 1838-1846-   [NPL 17] Parker K C, et al., (1994) J. Immunol.; 152(1):163-75.-   [NPL 18] Kuzushima K, et al., (2001) Blood; 98(6):1872-81.-   [NPL 19] Bachinsky M M, et. al., Cancer Immun. 2005 Mar. 22; 5:6.-   [NPL 20] Sener S F, et al. J Am Coll Surg 1999; 189:1-7.-   [NPL 21] Eloubeidi M A, et al. Am J Surg 2006; 192:322-9.-   [NPL 22] Goonetilleke K S, et al. Int J Surg 2007; 5:147-51.-   [NPL 23] Smeenk H G, et al. Langenbecks Arch Surg 2005; 390:94-103.-   [NPL 24] Yeo C J, et al. Ann Surg 1995; 221:721-31.-   [NPL 25] Lockhart A C, et al. Gastroenterology 2005; 128:1642-54.-   [NPL 26] Echard A, et al. Science 1998; 279:580-5.-   [NPL 27] Hirokawa N, et al. Curr Opin Cell Biol 1998; 10:60-73.-   [NPL 28] Allan V J, and Schroer T A. Curr Opin Cell Biol 1999;    11:476-82.-   [NPL 29] Taniuchi K, et al. Cancer Res 2005; 65:105-12.

SUMMARY OF INVENTION

The present invention is based in part on the discovery of new targetsof immunotherapy. Because TAAs have often no immunogenicity, thediscovery of appropriate targets is of extreme importance. Inparticular, the invention targets RAB6KIFL (SEQ ID NO: 2) encoded by thegene of GenBank Accession No. AF153329 or CR598555, also indicated byNM_(—)005733 (SEQ ID NO: 1)), since RAB6KIFL has been identified asup-regulated in several cancers such as bladder cancer, breast cancer,cholangiocellular carcinoma, esophageal cancer, non-small cell lungcancer (NSCLC), pancreatic cancer, prostate cancer, renal carcinoma andsmall cell lung cancer (SCLC). The present invention provides RAB6KIFLgene products containing epitope peptides that elicit surprisinglystrong CTL response that is specific to the corresponding molecules.Peripheral blood mononuclear cells (PBMCs) obtained from a healthy donorwere stimulated using the peptides of the present invention. The presentinvention further provides established CTLs that specifically recognizeHLA-A2 (A*0201) positive target cells pulsed with the respectivepeptides, and HLA-A2 (A*0201) restricted epitope peptides that caninduce potent and specific immune responses against RAB6KIFL expressedon tumor. These results demonstrate that RAB6KIFL is stronglyimmunogenic and the epitopes thereof are effective targets for tumorimmunotherapy.

Accordingly, it is an object of the present invention to provideoligopeptides having CTL inducibility as well as an amino acid sequenceselected from the group of SEQ ID NOs: 3, 4 and 5. In addition, inanother embodiment of the present invention, one, two or several aminoacids may be substituted, deleted, inserted and/or added, so long as theresulting modified oligopeptides retain the CTL inducibility of theoriginal peptides.

When administered to a subject, the present oligopeptides are presentedon the surface of antigen-expressing cells and then induce CTLstargeting the respective peptides. Therefore, it is an object of thepresent invention to provide antigen-presenting cells and exosomes thatpresent any of the present peptides, as well as methods for inducingantigen-presenting cells.

An anti-tumor immune response is induced by the administration of thepresent RAB6KIFL oligopeptides or polynucleotides encoding theoligopeptides, as well as exosomes and antigen-presenting cells whichpresent the RAB6KIFL oligopeptides. Therefore, it is yet another objectof the present invention to provide pharmaceutical agents orpharmaceutical composition containing the oligopeptides orpolynucleotides encoding them, as well as the exosomes andantigen-presenting cells as their active ingredients. The pharmaceuticalagents or pharmaceutical compositions of the present invention find useas vaccines.

Moreover, it is a further object of the present invention to providemethods for the treatment and/or prophylaxis of (i.e., prevention)cancers (tumors), and/or prevention of postoperative recurrence thereof,as well as methods for inducing CTLs, methods for inducing anti-tumorimmunity, such methods including the step of administering the RAB6KIFLoligopeptides, polynucleotides encoding RAB6KIFL oligopeptides, exosomesor the antigen-presenting cells presenting RAB6KIFL polypeptides or thepharmaceutical agents of the present invention. In addition, the CTLs ofthe present invention also find use as vaccines against cancer. Examplesof target cancers include, but are not limited to bladder cancer, breastcancer, cholangiocellular carcinoma, esophageal cancer, non-small celllung cancer (NSCLC), pancreatic cancer, prostate cancer, renal carcinomaand small cell lung cancer (SCLC).

It is to be understood that both the foregoing summary of the presentinvention and the following detailed description are of exemplifiedembodiments, and not restrictive of the invention or other alternateembodiments of the invention.

BRIEF DESCRIPTION OF DRAWINGS

Various aspects and applications of the present invention will becomeapparent to the skilled artisan upon consideration of the briefdescription of the figures and the detailed description of the presentinvention and its preferred embodiments which follows:

FIG. 1 depicts markedly and frequently enhanced expression of RAB6KIFLmRNA in pancreatic cancer tissues as based on a cDNA microarrayanalysis. A depicts a list of up-regulated genes in pancreatic cancercells. These genes were overexpressed in cancer cells in comparison totheir normal counterparts. The expression of RAB6KIFL mRNA in pancreaticcancer cells was markedly enhanced in all of 6 pancreatic cancerpatients. B depicts the relative expression ratio of RAB6KIFL gene innormal tissues based on a cDNA microarray analysis. RAB6KIFL gene wasfaintly expressed only in the testis and thymus. C depicts theexpression level of the RAB6KIFL gene was also enhanced in many lung andbladder cancers as well as pancreatic cancer based on the previous cDNAmicroarray analysis.

FIG. 2 depicts the analyses of RAB6KIFL mRNA expressed in human normaltissues, cancer cell lines, and cancer tissues. A depicts the expressionof RAB6KIFL mRNA was investigated in various normal tissues by usingRT-PCR analysis. RAB6KIFL mRNA was faintly expressed only in testis. Bdepicts the RT-PCR analysis of the RAB6KIFL expression in various cancercell lines. C depicts the RT-PCR analysis of the RAB6KIFL expression inpancreatic tumor tissues (T), and their normal counterparts (N). Theexpression of the RAB6KIFL gene was detected in 5 of 8 pancreatic cancertissues. In contrast, little expression was detected in their normalcounterparts.

FIG. 3 depicts pancreatic cancer-specific overexpression of RAB6KIFLprotein detected by Western blotting analyses. A depicts that RAB6KIFLprotein was not detected in eight normal tissues, whereas the testisgave a faint band that had a similar mobility with that observed inPANC1 cell lysate. B depicts that, in two pancreatic cancer patients,RAB6KIFL protein was detected in cancer tissues (T) but not in adjacentnormal tissues (N). Anti-beta-actin blotting was also performed tomonitor equal protein loading.

FIG. 4 depicts immunohistochemical analyses of RAB6KIFL protein inpancreatic cancer (A) and various normal tissues (B). A depicts strongstaining of RAB6KIFL was mainly observed at the cytoplasm and nuclei ofcancer cells in 6 of 9 cases, whereas very weak staining was observed inaciner cells and normal ductal epithelium of their normal adjacentpancreatic tissues. Similar strong staining was observed in themetastatic foci of the peritoneum. Little staining was detected intumor-forming pancreatitis. B depicts RAB6KIFL was not stained in thenormal brain, lung, liver, kidney, stomach, small intestine, colon,spleen, skeletal muscle, skin, and thymus. A possible faint staining wasobserved in testis. Positive staining signals are shown in brown color.The scale bars represent 100 micrometers.

FIG. 5 depicts identification of HLA-A2-restricted mouse CTL epitopes ofhuman RAB6KIFL by using HLA-A2.1 (HHD) Tgm. A depicts the HLA-A2.1 (HHD)Tgm were immunized with 5×10⁵ syngeneic BM-DCs pulsed with the twelvesets of the mixture of three kinds of peptides selected from 36candidate peptides in vivo at day 7 and 14. On day 21, CD4-spleen cellsisolated from immunized mice were stimulated with BM-DCs pulsed witheach peptide for 6 days. The CTL-produced IFN-gamma was detected by anELISPOT assay. RAB6KIFL-A2-9-12 (SEQ ID NO: 3), RAB6KIFL-A2-9-809 (SEQTD NO: 4), and RAB6KIFL-A2-10-284 (SEQ TD NO: 5) peptides were shown toinduce peptide-reactive CTLs. These assays were done twice with similarresults. B depicts immunohistochemical staining with anti-CD4 oranti-CD8 mAb in tissue specimens of HLA-A2 (HHD) Tgm immunized with theRAB6KIFL-A2-9-809 peptide. After two-times vaccination, these specimenswere resected and analyzed.

FIG. 6 depicts induction of RAB6KIFL-specific human CTL from the PBMCsof HLA-A2-positive healthy donors. A depicts that the RAB6KIFLpeptide-reactive CTLs were generated from the PBMCs of HLA-A2-positivehealthy donors. After three stimulations with autologousmonocyte-derived DCs pulsed with the RAB6KIFL-A2-9-12 (SEQ ID NO: 3),RAB6KIFL-A2-9-809 (SEQ ID NO:4), and RAB6KIFL-A2-10-284 (SEQ ID NO:5)peptide, the cytotoxicity of the CTLs against T2 cells (HLA-A2+, TAPdeficient), pulsed with each peptide or peptide-unpulsed T2 cells, wasdetected by standard a ⁵¹Cr release assay. These CTLs exhibitedcytotoxicity to the RAB6KIFL-A2-9-12 (left), RAB6KIFL-A2-9-809 (middle),and RAB6KIFL-A2-10-284 (right) peptide pulsed T2 cells, but not toirrelevant HIV peptide and peptide-unpulsed T2 cells. B depicts thatthese CTLs exhibited cytotoxicity to the RAB6KIFL+HLA-A2 (A*0201)⁺ humanpancreatic cancer cell line PANC1 and colon cancer cell line CaCo-2, butnot to RAB6KIFL+HLA-A2 (A*0201)⁻ human pancreatic cancer cell line PK8.

C depicts the cytotoxicity of these CTLs was RAB6KIFL-specific. TheseCTLs killed SKHep1/RAB6KIFL, a RAB6KIFL^(low) HLA-A2+ human liver cancercell line SKHep1 transfected with human RAB6KIFL gene, but not killedSKHep1/Mock. D depicts the inhibition of cytotoxicity by anti-HLA-classI mAb. After the target cells PANC1 were incubated with anti-HLA-class ImAb (W6/32, IgG_(2a)) or anti-HLA-DR mAb (H-DR-1, IgG_(2a)) respectivelyfor 1 hour, the CTLs generated from the PBMCs of healthy donor bystimulation with RAB6KIFL-A2-9-12 (upper), RAB6KIFL-A2-9-809 (middle),and RAB6KIFL-A2-10-284 (lower) peptide were added. IFN-gamma productionswere markedly inhibited by W6/32, but not by H-DR-1.

DESCRIPTION OF EMBODIMENTS

Although any methods and materials similar or equivalent to thosedescribed herein can be used in the practice or testing of embodimentsof the present invention, the preferred methods, devices, and materialsare now described. However, before the present materials and methods aredescribed, it is to be understood that the present invention is notlimited to the particular sizes, shapes, dimensions, materials,methodologies, protocols, etc. described herein, as these may vary inaccordance with routine experimentation and optimization. It is also tobe understood that the terminology used in the description is for thepurpose of describing the particular versions or embodiments only, andis not intended to limit the scope of the present invention which willbe limited only by the appended claims.

The disclosure of each publication, patent or patent applicationmentioned in this specification is specifically incorporated byreference herein in its entirety. However, nothing herein is to beconstrued as an admission that the invention is not entitled to antedatesuch disclosure by virtue of prior invention.

In case of conflict, the present specification, including definitions,will control. In addition, the materials, methods, and examples areillustrative only and not intended to be limiting.

I. DEFINITIONS

The words “a”, “an”, and “the” as used herein mean “at least one” unlessotherwise specifically indicated.

The terms “polypeptide”, “peptide” and “protein” are usedinterchangeably herein to refer to a polymer of amino acid residues. Theterms apply to amino acid polymers in which one or more amino acidresidue is a modified residue, or a non-naturally occurring residue,such as an artificial chemical mimetic of a corresponding naturallyoccurring amino acid, as well as to naturally occurring amino acidpolymers.

The term “oligopeptide” sometimes used in the present specification isused to refer to peptides of the present invention which are 20 residuesor fewer, typically 15 residues or fewer in length and usually consistof between about 8 and about 11 residues, often 9 or 10 residues.

The term “amino acid” as used herein refers to naturally occurring andsynthetic amino acids, as well as amino acid analogs and amino acidmimetics that similarly function to the naturally occurring amino acids.Naturally occurring amino acids are those encoded by the genetic code,as well as those modified after translation in cells (e.g.,hydroxyproline, gamma-carboxyglutamate, and O-phosphoserine). The phrase“amino acid analog” refers to compounds that have the same basicchemical structure (an alpha carbon bound to a hydrogen, a carboxygroup, an amino group, and an R group) as a naturally occurring aminoacid but have a modified R group or modified backbones (e.g.,homoserine, norleucine, methionine, sulfoxide, methionine methylsulfonium). The phrase “amino acid mimetic” refers to chemical compoundsthat have different structures but similar functions to general aminoacids.

Amino acids may be referred to herein by their commonly known threeletter symbols or the one-letter symbols recommended by the IUPAC-IUBBiochemical Nomenclature Commission.

The terms “gene”, “polynucleotides”, “nucleotides” and “nucleic acids”are used interchangeably herein unless otherwise specifically indicatedand are similarly to the amino acids referred to by their commonlyaccepted single-letter codes.

Unless otherwise defined, the terms “cancer” refers to cancersover-expressing the RAB6KIFL gene. Examples of cancers over-expressingRAB6KIFL include, but are not limited to, bladder cancer, breast cancer,cholangiocellular carcinoma, esophageal cancer, non-small cell lungcancer (NSCLC), pancreatic cancer, prostate cancer, renal carcinoma andsmall cell lung cancer (SCLC).

Unless otherwise defined, the term “cytotoxic T lymphocyte”, “cytotoxicT cell” and “CTL” are used interchangeably herein and, unless otherwisespecifically indicated, refer to a sub-group of T lymphocytes that arecapable of recognizing non-self cells (e.g., tumor cells, virus-infectedcells) and inducing the death of such cells.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs.

II. PEPTIDES

To demonstrate that peptides derived from RAB6KIFL function as anantigen recognized by cytotoxic T lymphocytes (CTLs), peptides derivedfrom RAB6KIFL (SEQ ID NO: 2) were analyzed to determine whether theywere antigen epitopes restricted by HLA-A2 (A*0201) which are commonlyencountered HLA alleles (Date Y et al., Tissue Antigens 47: 93-101,1996; Kondo A et al., J Immunol 155: 4307-12, 1995; Kubo R T et al., JImmunol 152: 3913-24, 1994). Candidates of HLA-A2 binding peptidesderived from RAB6KIFL were identified using the information on theirbinding affinities to HLA-A2. After in vitro stimulation of T-cells bydendritic cells (DCs) loaded with these peptides, CTLs were successfullyestablished using each of the peptides, particularly following peptides:

RAB6KIFL-A2-9-12, (SEQ ID NO: 3) RAB6KIFL-A2-9-809, (SEQ ID NO: 4) andRAB6KIFL-A2-10-284. (SEQ ID NO: 5)

These established CTLs show potent specific CTL activity against targetcells pulsed with respective peptides. The results herein demonstratethat RAB6KIFL is an antigen recognized by CTL and that the peptides maybe epitope peptides of RAB6KIFL restricted by HLA-A2 (A*0201).

Since the RAB6KIFL gene is over expressed in most cancer tissues, suchas bladder cancer, breast cancer, cholangiocellular carcinoma,esophageal cancer, non-small cell lung cancer (NSCLC), pancreaticcancer, prostate cancer, renal carcinoma and small cell lung cancer(SCLC), it is a good target for immunotherapy. Thus, the presentinvention provides oligopeptides such as nonapeptides (peptidesconsisting of nine amino acid residues) and decapeptides (peptidesconsisting of ten amino acid residues) corresponding to CTL-recognizedepitopes of RAB6KIFL. Particularly preferred examples of oligopeptidesof the present invention include those peptides having an amino acidsequence selected from among SEQ ID NOs: 3, 4 and 5.

Generally, software programs now available on the Internet, such asthose described in Parker K C et al., J Immunol 1994 Jan. 1, 152(1):163-75, can be used to calculate the binding affinities between variouspeptides and HLA antigens in silico. Binding affinity with HLA antigenscan be measured as described, for example, in Parker K C et al., JImmunol 1994 Jan. 1, 152(1): 163-75; and Kuzushima K et al., Blood 2001,98(6): 1872-81. The methods for determining binding affinity isdescribed, for example, in; Journal of Immunological Methods, 1995, 185:181-190; Protein Science, 2000, 9: 1838-1846. Thus, the presentinvention encompasses peptides of RAB6KIFL which are determined to bindwith HLA antigens by such known programs.

Furthermore, these peptides of the present invention can be flanked withadditional amino acid residues so long as the peptide retains its CTLinducibility. Such peptides with CTL inducibility are, for example, lessthan about 40 amino acids, often less than about 20 amino acids, usuallyless than about 15 amino acids. The amino acid sequence flanking thepeptides consisting of the amino acid sequence selected from the groupof SEQ ID NOs: 3, 4 and 5 is not limited and can be composed of any kindof amino acids so long as it does not impair the CTL inducibility of theoriginal peptide. Thus, the present invention also provides peptideshaving CTL inducibility, which comprises the amino acid sequenceselected from the group of SEQ TD NOs: 3, 4 and 5.

In general, modification of one, two, or several amino acids in aprotein will not influence the function of the protein, or in some caseseven enhance the desired function of the original protein. In fact,modified peptides (i.e., peptides composed of an amino acid sequence inwhich one, two or several amino acid residues have been modified (i.e.,substituted, deleted, added and/or inserted) as compared to an originalreference sequence) have been known to retain the biological activity ofthe original peptide (Mark et al., Proc Natl Acad Sci USA 1984, 81:5662-6; Zoller and Smith, Nucleic Acids Res 1982, 10: 6487-500;Dalbadie-McFarland et al., Proc Natl Acad Sci USA 1982, 79: 6409-13).Thus, in one embodiment, the oligopeptides of the present invention mayhave both CTL inducibility and an amino acid sequence selected from thegroup of SEQ ID NOs: 3, 4 and 5 wherein one, two or several amino acidsare added, inserted, deleted, and/or substituted.

Those of skill in the art recognize that individual additions orsubstitutions to an amino acid sequence which alters a single amino acidor a small percentage of amino acids tend to result in the conservationof the properties of the original amino acid side-chain. As such, theyare conventionally referred to as “conservative substitutions” or“conservative modifications”, wherein the alteration of a proteinresults in a modified protein having properties and functions analogousto the original protein. Conservative substitution tables providingfunctionally similar amino acids are well known in the art. Examplesamino acid side chain characteristics that are desirable to conserveinclude, for example, hydrophobic amino acids (A, I, L, M, F, P, W, Y,V), hydrophilic amino acids (R, D, N, C, E, Q, G, H, K, S, T), and sidechains having the following functional groups or characteristics incommon: an aliphatic side-chain (G, A, V, L, I, P); a hydroxyl groupcontaining side-chain (S, T, Y); a sulfur atom containing side-chain (C,M); a carboxylic acid and amide containing side-chain (D, N, E, Q); abase containing side-chain (R, K, H); and an aromatic containingside-chain (H, F, Y, W). In addition, the following eight groups eachcontain amino acids that are accepted in the art as conservativesubstitutions for one another:

1) Alanine (A), Glycine (G);

2) Aspartic acid (D), Glutamic acid (E);

3) Aspargine (N), Glutamine (Q);

4) Arginine (R), Lysine (K);

5) Isoleucine (I), Leucine (L), Methionine (M), Valine (V);

6) Phenylalanine (F), Tyrosine (Y), Tryptophan (W);

7) Serine (S), Threonine (T); and

8) Cysteine (C), Methionine (M) (see, e.g., Creighton, Proteins 1984).

Such conservatively modified peptides are also considered to be peptidesof the present invention. However, peptides of the present invention arenot restricted thereto and can include non-conservative modifications,so long as the peptide retains the CTL inducibility of the originalpeptide. Furthermore, modified peptides should not exclude CTL induciblepeptides of polymorphic variants, interspecies homologues, and allelesof RAB6KIFL.

To retain the requisite CTL inducibility one can modify (add orsubstitute) a small number (for example, 1, 2 or several) or a smallpercentage of amino acids. Herein, the term “several” means 5 or feweramino acids, for example, 3 or fewer. The percentage of amino acids tobe modified can be 20% or less, for example, 15% of less, for example10% or 1 to 5%.

When used in the context of immunotherapy, peptides of the presentinvention should be presented on the surface of a cell or exosome,preferably as a complex with an HLA antigen. Therefore, t is preferableto select peptides that not only induce CTLs but also that possess highbinding affinity to the HLA antigen. To that end, the peptides can bemodified by substitution, insertion, deletion, and/or addition of theamino acid residues to yield a modified peptide having improved bindingaffinity. In addition to peptides that are naturally displayed, sincethe regularity of the sequences of peptides displayed by binding to HLAantigens is already known (J Immunol 1994, 152: 3913; Immunogenetics1995, 41: 178; J Immunol 1994, 155: 4307), modifications based on suchregularity can be introduced into the immunogenic peptides of theinvention. For example, peptides possessing high HLA-A2 (A*0201) bindingaffinity have their second amino acid from the N-terminus substitutedwith leucine or methionine, and peptides whose amino acid at C-terminusis substituted with valine or leucine. Thus, peptides having the aminoacid sequences of SEQ ID NOs: 3, 4 or 5 wherein the second amino acidfrom the N-terminus is substituted with leucine or methionine and/orwherein the C-terminus is substituted with valine or leucine, areencompassed by the present invention. Substitutions can be introducednot only at the terminal amino acids but also at the position ofpotential TCR recognition of peptides. Several studies have demonstratedthat amino acid substitutions in a peptide can be equal to or betterthan the original, for example CAP1, p53₍₂₆₄₋₂₇₂₎, Her-2/neu₍₃₆₉₋₃₇₇₎ orgp100₍₂₀₉₋₂₁₇₎ (Zaremba et al. Cancer Res. 57, 4570-4577, 1997, T. K.Hoffmann et al. J. Immunol. (2002) Feb. 1; 168(3):1338-47, S. O. Dionneet al. Cancer Immunol immunother. (2003) 52: 199-206 and S. O. Dionne etal. Cancer Immunology, Immunotherapy (2004) 53, 307-314).

The present invention also contemplates the addition of amino acids tothe sequences disclosed here. For example, one, two or several aminoacids can also be added to the N and/or C-terminus of the presentpeptides. Such modified peptides having high HLA antigen bindingaffinity and retained CTL inducibility are also included in the presentinvention.

However, when the peptide sequence is identical to a portion of theamino acid sequence of an endogenous or exogenous protein having adifferent function, side effects such as autoimmune disorders and/orallergic symptoms against specific substances may be induced. Therefore,it is preferable to first perform homology searches using availabledatabases to avoid situations in which the sequence of the peptidematches the amino acid sequence of another protein. When it becomesclear from the homology searches that no peptide exists with as few as 1or 2 amino acid differences as compared to the objective peptide, theobjective peptide can be modified in order to increase its bindingaffinity with HLA antigens, and/or increase its CTL inducibility withoutany danger of such side effects.

Although peptides having high binding affinity to the HLA antigens asdescribed above are expected to be highly effective, the candidatepeptides, which are selected according to the presence of high bindingaffinity as an indicator, are further examined for the presence of CTLinducibility. Herein, the phrase “CTL inducibility” indicates theability of the peptide to induce cytotoxic lymphocytes (CTLs) whenpresented on antigen-presenting cells. Further, “CTL inducibility”includes the ability of the peptide to induce CTL activation, CTLproliferation, promote CTL lysis of target cells, and to increase CTLIFN-gamma production.

Confirmation of CTL inducibility is accomplished by inducingantigen-presenting cells carrying human MHC antigens (for example,B-lymphocytes, macrophages, and dendritic cells (DCs)), or morespecifically DCs derived from human peripheral blood mononuclearleukocytes, and after stimulation with the peptides, mixing withCD8-positive cells, and then measuring the IFN-gamma produced andreleased by CTL against the target cells. As the reaction system,transgenic animals that have been produced to express a human HLAantigen (for example, those described in BenMohamed L, Krishnan R,Longmate J, Auge C, Low L, Primus J, Diamond D J, Hum Immunol 2000August, 61(8): 764-79, Related Articles, Books, Linkout Induction of CTLresponse by a minimal epitope vaccine in HLA A*0201/DR1 transgenic mice:dependence on HLA class II restricted T(H) response) can be used. Forexample, the target cells can be radio-labeled with ⁵¹Cr and such, andcytotoxic activity can be calculated from radioactivity released fromthe target cells. Alternatively, CTL inducibility can be assessed bymeasuring IFN-gamma produced and released by CTL in the presence ofantigen-presenting cells (APCs) that carry immobilized peptides, andvisualizing the inhibition zone on the media using anti-IFN-gammamonoclonal antibodies.

As a result of examining the CTL inducibility of the peptides asdescribed above, it was discovered that those peptides having highbinding affinity to an HLA antigen did not necessarily have high CTLinducibility. However, of those peptides identified and assessed,nonapeptides or decapeptides selected from peptides having an amino acidsequences indicated by SEQ ID NOs: 3, 4 and 5, were found to exhibitparticularly high CTL inducibility as well as high binding affinity toan HLA antigen. Thus, these peptides are exemplified as preferredembodiments of the present invention.

In addition to the above-described modifications, the peptides of thepresent invention can also be linked to other substances, so long as theresulting linked peptide retains the requisite CTL inducibility of theoriginal peptide. Examples of suitable substances include, but are notlimited to: peptides, lipids, sugar and sugar chains, acetyl groups,natural and synthetic polymers, etc. The peptides can containmodifications such as glycosylation, side chain oxidation, orphosphorylation, etc. provided the modifications do not destroy thebiological activity of the original peptide. These kinds ofmodifications can be performed to confer additional functions (e.g.,targeting function, and delivery function) or to stabilize thepolypeptide.

For example, to increase the in vivo stability of a polypeptide, it isknown in the art to introduce D-amino acids, amino acid mimetics orunnatural amino acids; this concept can also be adapted to the presentpolypeptides. The stability of a polypeptide can be assayed in a numberof ways. For instance, peptidases and various biological media, such ashuman plasma and serum, can be used to test stability (see, e.g.,Verhoef et al., Eur J Drug Metab Pharmacokin 1986, 11: 291-302).

Further, the peptides of the present invention may be linked to otherpeptides via spacers or linkers. Examples of other peptides include, butare not limited to, CTL inducible peptides derived from other TAAs.Alternatively, two or more peptides of the present invention may belinked via spacers or linkers. The peptides linked via spacers orlinkers may be the same or different each other. Spacers or linkers arenot specifically limited, but are preferably peptides, more preferablypeptides having one or more cleavage sites which are capable of beingcleaved by enzymes such as peptidases, proteases and proteasomes.Examples of linkers or spacers include, but are not limited to: AAY (P.M. Daftarian et al., J Trans Med 2007, 5:26), AAA, NKRK (R. P. M.Sutmuller et al., J. Immunol. 2000, 165: 7308-7315) or, one to severallysine residues (S. Ota et al., Can Res. 62, 1471-1476, K. S. Kawamuraet al., J. Immunol. 2002, 168: 5709-5715). The peptides of the presentinvention encompass those peptides linked to other peptides via spacersor linkers.

Herein, the peptides of the present invention can also be described as“RAB6KIFL peptide(s)”, “RAB6KIFL polypeptide(s)” or “RAB6KIFLoligopeptide”.

III. PREPARATION OF RAB6KIFL PEPTIDES

The peptides of the present invention can be prepared using well knowntechniques. For example, the peptides can be prepared synthetically,using recombinant DNA technology or chemical synthesis. The peptides ofthe present invention can be synthesized individually or as longerpolypeptides composed of two or more peptides. The peptides can then beisolated i.e., purified or isolated so as to be substantially free ofother naturally occurring host cell proteins and fragments thereof, orany other chemical substances.

A peptide of the present invention can be obtained through chemicalsynthesis based on the selected amino acid sequence. Examples ofconventional peptide synthesis methods that can be adapted to thesynthesis include, but are not limited to:

(i) Peptide Synthesis, Interscience, New York, 1966;

(ii) The Proteins, Vol. 2, Academic Press, New York, 1976;

(iii) Peptide Synthesis (in Japanese), Maruzen Co., 1975;

(iv) Basics and Experiment of Peptide Synthesis (in Japanese), MaruzenCo., 1985;

(v) Development of Pharmaceuticals (second volume) (in Japanese), Vol.14 (peptide synthesis), Hirokawa, 1991;

(vi) WO99/67288; and

(vii) Barany G. & Merrifield R. B., Peptides Vol. 2, “Solid PhasePeptide Synthesis”, Academic Press, New York, 1980, 100-118.

Alternatively, the present peptides can be obtained adapting any knowngenetic engineering methods for producing peptides (e.g., Morrison J, JBacteriology 1977, 132: 349-51; Clark-Curtiss & Curtiss, Methods inEnzymology (eds. Wu et al.) 1983, 101: 347-62). For example, first, asuitable vector harboring a polynucleotide encoding the objectivepeptide in an expressible form (e.g., downstream of a regulatorysequence corresponding to a promoter sequence) is prepared andtransformed into a suitable host cell. The host cell is then cultured toproduce the peptide of interest. The peptide can also be produced invitro adopting an in vitro translation system.

IV. POLYNUCLEOTIDES

The present invention also provides a polynucleotide which encodes anyof the aforementioned peptides of the present invention. These includepolynucleotides derived from the natural occurring RAB6KIFL/KIF20A gene(GenBank Accession No. NM_(—)005733 (SEQ ID NO: 1)) as well as thosehaving a conservatively modified nucleotide sequence thereof. Herein,the phrase “conservatively modified nucleotide sequence” refers tosequences which encode identical or essentially identical amino acidsequences. Due to the degeneracy of the genetic code, a large number offunctionally identical nucleic acids encode any given protein. Forinstance, the codons GCA, GCC, GCG, and GCU all encode the amino acidalanine. Thus, at every position where an alanine is specified by acodon, the codon can be altered to any of the corresponding codonsdescribed without altering the encoded polypeptide. Such nucleic acidvariations are “silent variations,” which are one species ofconservatively modified variations. Every nucleic acid sequence hereinwhich encodes a peptide also describes every possible silent variationof the nucleic acid. One of ordinary skill will recognize that eachcodon in a nucleic acid (except AUG, which is ordinarily the only codonfor methionine, and TGG, which is ordinarily the only codon fortryptophan) can be modified to yield a functionally identical molecule.Accordingly, each silent variation of a nucleic acid that encodes apeptide is implicitly described in each disclosed sequence.

The polynucleotide of the present invention can be composed of DNA, RNA,and derivatives thereof. A DNA is suitably composed of bases such as A,T, C, and G, and T is replaced by U in an RNA.

The polynucleotide of the present invention can encode multiple peptidesof the present invention with or without intervening amino acidsequences in between. For example, the intervening amino acid sequencecan provide a cleavage site (e.g., enzyme recognition sequence) of thepolynucleotide or the translated peptides. Furthermore, thepolynucleotide can include any additional sequences to the codingsequence encoding the peptide of the present invention. For example, thepolynucleotide can be a recombinant polynucleotide that includesregulatory sequences required for the expression of the peptide or canbe an expression vector (plasmid) with marker genes and such. Ingeneral, such recombinant polynucleotides can be prepared by themanipulation of polynucleotides through conventional recombinanttechniques using, for example, polymerases and endonucleases.

Both recombinant and chemical synthesis techniques can be used toproduce the polynucleotides of the present invention. For example, apolynucleotide can be produced by insertion into an appropriate vector,which can be expressed when transfected into a competent cell.Alternatively, a polynucleotide can be amplified using PCR techniques orexpression in suitable hosts (see, e.g., Sambrook et al., MolecularCloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York,1989). Alternatively, a polynucleotide can be synthesized using thesolid phase techniques, as described in Beaucage S L & Iyer R P,Tetrahedron 1992, 48: 2223-311; Matthes et al., EMBO J 1984, 3: 801-5.

Vectors containing the polynucleotide of the present invention and hostcells harboring the vectors are also included in the present invention.

V. EXOSOMES

The present invention further provides intracellular vesicles calledexosomes, which present complexes formed between the peptides of thisinvention and HLA antigens on their surface. Exosomes can be prepared,for example by using the methods detailed in Japanese Patent ApplicationKohyo Publications Nos. Hei 11-510507 and WO99/03499, and can beprepared using APCs obtained from patients who are subject to treatmentand/or prevention. The exosomes of this invention can be inoculated asvaccines, in a fashion similar to the peptides of this invention.

The type of HLA antigens comprised in the complexes must match that ofthe subject requiring treatment and/or prevention. The use of HLA-A2type that is highly expressed among the Japanese and Caucasian isfavorable for obtaining effective results, and subtypes such as HLA-A2(A*0201) and HLA-A2 (A*0206) find use. Typically, in the clinic, thetype of HLA antigen of the patient requiring treatment is investigatedin advance, which enables appropriate selection of peptides having highlevels of binding affinity to this antigen, or having CTL inducibilityby antigen presentation. Furthermore, in order to obtain peptidesshowing high binding affinity and CTL inducibility, substitution oraddition of 1, 2, or several amino acids can be performed based on theamino acid sequence of the naturally occurring RAB6KIFL partial peptide.

When using HLA-A2 (A*0201) antigen for the exosome of the presentinvention, a peptide having the sequence selected peptide of SEQ ID NO:3, 4 and 5 finds use.

VI. ANTIGEN-PRESENTING CELLS (APCS)

The present invention also provides isolated APCs that present complexesformed between HLA antigens and the peptides of this invention on itssurface. The APCs that are obtained by contacting the peptides of thisinvention, or introducing the polynucleotides encoding the peptides ofthis invention in an expressible form can be derived from patients whoare subject to treatment and/or prevention, and can be administered asvaccines by themselves or in combination with other drugs including thepeptides of this invention, exosomes, or cytotoxic T cells.

The APCs are not limited to a particular kind of cells and includedendritic cells (DCs), Langerhans cells, macrophages, B cells, andactivated T cells, which are known to present proteinaceous antigens ontheir cell surface so as to be recognized by lymphocytes. Since DC is arepresentative APC having the strongest CTL inducing action among APCs,DCs find use as the APCs of the present invention.

For example, an APC can be obtained by inducing DCs from peripheralblood monocytes and then contacting (stimulating) them with the peptidesof this invention in vitro, ex vivo or in vivo. When the peptides ofthis invention are administered to the subjects, APCs that present thepeptides of this invention are induced in the body of the subject. Thephrase “inducing APC” includes contacting (stimulating) a cell with thepeptides of this invention, or nucleotides encoding the peptides of thisinvention to present complexes formed between HLA antigens and thepeptides of this invention on cell's surface. Alternatively, afterintroducing the peptides of this invention to the APCs to allow the APCsto present the peptides, the APCs can be administered to the subject asa vaccine. For example, the ex vivo administration can include the stepsof:

a: collecting APCs from a first subject:

b: contacting with the APCs of step a, with the peptide; and

c: administering the peptide-loaded APCs to a second subject.

The first subject and the second subject can be the same individual, ormay be different individuals. Alternatively, according to the presentinvention, use of the peptides of this invention for manufacturing apharmaceutical composition inducing antigen-presenting cells isprovided. In addition, the present invention provides a method orprocess for manufacturing a pharmaceutical composition for inducingantigen-presenting cells, wherein the method includes the step ofadmixing or formulating the peptide of the present invention with apharmaceutically acceptable carrier. Alternatively, the presentinvention provides a method or process for manufacturing apharmaceutical composition for treating cancers including bladdercancer, breast cancer, cholangiocellular carcinoma, esophageal cancer,non-small cell lung cancer (NSCLC), pancreatic cancer, prostate cancer,renal carcinoma and small cell lung cancer (SCLC), wherein the methodincludes the step of admixing or formulating the peptide of the presentinvention with a pharmaceutically acceptable carrier. Further, thepresent invention also provides the peptides of the present inventionfor inducing antigen-presenting cells. The APCs obtained by step b canbe administered to the subject as a vaccine. Alternatively, the presentinvention provides the peptides for treating cancers including bladdercancer, breast cancer, cholangiocellular carcinoma, esophageal cancer,non-small cell lung cancer (NSCLC), pancreatic cancer, prostate cancer,renal carcinoma and small cell lung cancer (SCLC).

According to an aspect of the present invention, the APCs of the presentinvention have a high level of CTL inducibility. In the term of “highlevel of CTL inducibility”, the high level is relative to the level ofthat by APC contacting with no peptide or peptides which can not inducethe CTL. Such APCs having a high level of CTL inducibility can beprepared by a method which includes the step of transferring genescontaining polynucleotides that encode the peptides of this invention toAPCs in vitro. The introduced genes can be in the form of DNAs or RNAs.Examples of methods for introduction include, without particularlimitations, various methods conventionally performed in this field,such as lipofection, electroporation, and calcium phosphate method canbe used. More specifically, it can be performed as described in CancerRes 1996, 56: 5672-7; J Immunol 1998, 161: 5607-13; J Exp Med 1996, 184:465-72; Published Japanese Translation of International Publication No.2000-509281. By transferring the gene into APCs, the gene undergoestranscription, translation, and such in the cell, and then the obtainedprotein is processed by MHC Class I or Class II, and proceeds through apresentation pathway to present peptides.

In a preferred embodiment, the APCs of the present invention present onits surface a complex of an HLA antigen and a oligopeptide comprising anamino acid sequence selected from among SEQ ID NO: 3, 4 and 5.Preferably, the APCs of the present invention carry HLA-A2 antigen, inparticular HLA-A2 (A*0201) on its surface. Alternatively, oligopeptideto form complex with an HLA antigen may be a oligopeptide comprising anamino acid sequence selected from among SEQ ID NO: 3, 4, and 5, whereinone, two or several amino acids are substituted, inserted, deletedand/or added, for example, the second amino acid from the N-terminus maybe substituted with leucine or methionine, and/or the C-terminal aminoacid may be substituted with valine or leucine.

VII. CYTOTOXIC T CELLS (CTLS)

A cytotoxic T cell induced against any of the peptides of the presentinvention strengthens the immune response targeting tumor-associatedendothelia in vivo and thus can be used as vaccines, in a fashionsimilar to the peptides per se. Thus, the present invention alsoprovides isolated cytotoxic T cells that are specifically induced oractivated by any of the present peptides.

Such cytotoxic T cells can be obtained by (1) administering to asubject, and then collecting cytotoxic T cells from the subject, or (2)contacting (stimulating) subject-derived APCs, and CD8-positive cells,or peripheral blood mononuclear leukocytes in vitro with the peptides ofthe present invention and then isolating cytotoxic T cells.

The cytotoxic T cells, which have been induced by stimulation from APCsthat present the peptides of this invention, can be derived frompatients who are subject to treatment and/or prevention, and can beadministered by themselves or in combination with other drugs includingthe peptides of this invention or exosomes for the purpose of regulatingeffects. The obtained cytotoxic T cells act specifically against targetcells presenting the peptides of this invention, or for example, thesame peptides used for induction. In the other word, the cytotoxic Tcells can recognize (i.e., binding to) a complex formed between a HLAantigen and the peptide of the present invention on a target cellsurface with the T cell receptor, and then attack the target cell toinduce the death of the target cell. The target cells can be cells thatendogenously express RAB6KIFL, or cells that are transfected with theRAB6KIFL gene; and cells that present a peptide of this invention on thecell surface due to stimulation by the peptide can also serve as targetsof activated CTL attack. In the preferred embodiment, the target cellscarry HLA-A2 antigen, in particular HLA-A2 (A*020) on its surface.

VIII. T CELL RECEPTOR (TCR)

The present invention also provides a composition composed of a nucleicacid sequence encoding polypeptides that are capable of forming asubunit of a T cell receptor (TCR), and methods of using the same. TheTCR alpha and beta have the ability to form TCR that confer specificityto T cells against tumor cells expressing RAB6KIFL. By using the knownmethods in the art, the nucleic acid sequence of TCR alpha and betachains of the TCR expressed in the CTL induced with one or more peptidesof this invention can be isolated and used to construct suitable vectorsthat can mediate high efficiency gene transfer into primary humanlymphocytes (WO2007/032255 and Morgan R A, et al., J Immunol, 171, 3287(2003)). For example, these vectors are retroviral vectors.Advantageously, the invention provides an off-the-shelf compositionallowing rapid modification of a patient's own T cells (or those ofanother mammal) to rapidly and easily produce modified T cells havingexcellent cancer cell killing properties.

Also, the present invention provides CTLs which are prepared bytransduction with the nucleic acids encoding the TCR subunitspolypeptides that bind to the RAB6KIFL peptide e.g. SEQ ID NOs: 3, 4 and5 in the context of HLA-A2 (A*0201). The transduced CTLs are capable ofhoming to cancer cells in vivo, and can be expanded by well knownculturing methods in vitro (e.g., Kawakami et al., J Immunol., 142,3452-3461 (1989)). The T cells of the invention can be used to form animmunogenic composition useful in treating or the prevention of cancerin a patient in need of therapy or protection (WO2006/031221).

IX. PHARMACEUTICAL AGENTS OR COMPOSITIONS

The terms “prevention” and “prophylaxis” are interchangeably used hereinto refer to any activity that reduces the burden of mortality ormorbidity from disease. Prevention and prophylaxis can occur “atprimary, secondary and tertiary prevention levels.” While primaryprevention and prophylaxis avoid the development of a disease, secondaryand tertiary levels of prevention and prophylaxis encompass activitiesaimed at the prevention and prophylaxis of the progression of a diseaseand the emergence of symptoms as well as reducing the negative impact ofan already established disease by restoring function and reducingdisease-related complications. Alternatively, prevention and prophylaxiscan include a wide range of prophylactic therapies aimed at alleviatingthe severity of the particular disorder, e.g. reducing the proliferationand metastasis of tumors.

The treatment and/or prophylaxis of cancer and/or the prevention ofpostoperative recurrence thereof include any of the following steps,such as the surgical removal of cancer cells, the inhibition of thegrowth of cancerous cells, the involution or regression of a tumor, theinduction of remission and suppression of occurrence of cancer, thetumor regression, and the reduction or inhibition of metastasis.Effectively treating and/or the prophylaxis of cancer decreasesmortality and improves the prognosis of individuals having cancer,decreases the levels of tumor markers in the blood, and alleviatesdetectable symptoms accompanying cancer. For example, reduction orimprovement of symptoms constitutes effectively treating and/or theprophylaxis include 10%, 20%, 30% or more reduction, or stable disease.

Since RAB6KIFL expression is up-regulated in several cancers as comparedwith normal tissue, the peptides of this invention or polynucleotidesencoding such peptides can be used for the treatment and/or for theprophylaxis of cancer, and/or prevention of postoperative recurrencethereof. Thus, the present invention provides a pharmaceutical agent orcomposition for treating and/or for preventing of cancer, and/orpreventing the postoperative recurrence thereof, which includes one ormore of the peptides of this invention, or polynucleotides encoding thepeptides as an active ingredient. Alternatively, the present peptidescan be expressed on the surface of any of the foregoing exosomes orcells, such as APCs for the use as pharmaceutical agents or composition.In addition, the aforementioned cytotoxic T cells which target any ofthe peptides of the present invention can also be used as the activeingredient of the present pharmaceutical agents or composition. In thecontext of the present invention, the phrase “targeting a peptide”refers to recognizing (i.e., binding to) a complex formed between a HLAantigen and a peptide on a target cell surface with the T cell receptor,and then attacking the target cell to induce the death of the targetcell.

In another embodiment, the present invention also provides the use of anactive ingredient selected from among:

(a) a peptide of the present invention,

(b) a nucleic acid encoding such a peptide as disclosed herein in anexpressible form,

(c) an APC of the present invention, and

(d) a cytotoxic T cells of the present invention in manufacturing apharmaceutical composition or agent for treating cancer.

Alternatively, the present invention further provides an activeingredient selected from among:

(a) a peptide of the present invention,

(b) a nucleic acid encoding such a peptide as disclosed herein in anexpressible form,

(c) an APC of the present invention, and

(d) a cytotoxic T cells of the present invention for use in treatingcancer.

Alternatively, the present invention further provides a method orprocess for manufacturing a pharmaceutical composition or agent fortreating cancer, wherein the method or process includes the step offormulating a pharmaceutically or physiologically acceptable carrierwith an active ingredient selected from among:

(a) a peptide of the present invention,

(b) a nucleic acid encoding such a peptide as disclosed herein in anexpressible form,

(c) an APC of the present invention, and

(d) a cytotoxic T cells of the present invention as active ingredients.

In another embodiment, the present invention also provides a method orprocess for manufacturing a pharmaceutical composition or agent fortreating cancer, wherein the method or process includes the step ofadmixing an active ingredient with a pharmaceutically or physiologicallyacceptable carrier, wherein the active ingredient is selected fromamong:

(a) a peptide of the present invention,

(b) a nucleic acid encoding such a peptide as disclosed herein in anexpressible form,

(c) an APC of the present invention, and

(d) a cytotoxic T cells of the present invention.

Alternatively, the pharmaceutical composition or agent of the presentinvention may be used for either or both the prophylaxis of cancer andprevention of postoperative recurrence thereof.

The present pharmaceutical agents or compositions find use as a vaccine.In the context of the present invention, the phrase “vaccine” (alsoreferred to as an immunogenic composition) refers to a substance thathas the function to induce anti-tumor immunity upon inoculation intoanimals.

The pharmaceutical agents or compositions of the present invention canbe used to treat and/or prevent cancers, and/or prevention ofpostoperative recurrence thereof in subjects or patients including humanand any other mammal including, but not limited to, mouse, rat,guinea-pig, rabbit, cat, dog, sheep, goat, pig, cattle, horse, monkey,baboon, and chimpanzee, particularly a commercially important animal ora domesticated animal.

According to the present invention, oligopeptides having an amino acidsequence selected from among SEQ ID NOs: 3, 4 and 5 have been found tobe HLA-A2 (A*0201)-restricted epitope peptides, that can induce potentand specific immune response. Therefore, the present pharmaceuticalagents or compositions which include any of these oligopeptides with theamino acid sequences of SEQ ID NOs: 3, 4 or 5 are particularly suitedfor the administration to subjects whose HLA antigen is HLA-A2 (A*0201).The same applies to pharmaceutical agents or compositions which includepolynucleotides encoding any of these oligopeptides.

Cancers to be treated by the pharmaceutical agents or compositions ofthe present invention are not limited and include all kinds of cancerswherein RAB6KIFL is involved, including for example, bladder cancer,breast cancer, cholangiocellular carcinoma, esophageal cancer, non-smallcell lung cancer (NSCLC), pancreatic cancer, prostate cancer, renalcarcinoma and small cell lung cancer (SCLC). In particular, thepharmaceutical agents or compositions of the present invention arepreferably applied to pancreatic cancer.

The present pharmaceutical agents or compositions can contain inaddition to the aforementioned active ingredients, other peptides whichhave the ability to induce CTLs against cancerous cells, otherpolynucleotides encoding the other peptides, other cells that presentthe other peptides, or such. Herein, the other peptides that have theability to induce CTLs against cancerous cells are exemplified by cancerspecific antigens (e.g., identified TAAs), but are not limited thereto.

If needed, the pharmaceutical agents or compositions of the presentinvention can optionally include other therapeutic substances as anactive ingredient, so long as the substance does not inhibit theantitumoral effect of the active ingredient, e.g., any of the presentpeptides. For example, formulations can include anti-inflammatory agentsor compositions, pain killers, chemotherapeutics, and the like. Inaddition to including other therapeutic substances in the medicamentitself, the medicaments of the present invention can also beadministered sequentially or concurrently with the one or more otherpharmacologic agents or compositions. The amounts of medicament andpharmacologic agent or compositions depend, for example, on what type ofpharmacologic agent(s) or compositions(s) is/are used, the disease beingtreated, and the scheduling and routes of administration.

It should be understood that in addition to the ingredients particularlymentioned herein, the pharmaceutical agents or compositions of thisinvention can include other agents or compositions conventional in theart having regard to the type of formulation in question.

In one embodiment of the present invention, the present pharmaceuticalagents or compositions can be included in articles of manufacture andkits containing materials useful for treating the pathologicalconditions of the disease to be treated, e.g, cancer. The article ofmanufacture can include a container of any of the present pharmaceuticalagents or compositions with a label. Suitable containers includebottles, vials, and test tubes. The containers can be formed from avariety of materials, such as glass or plastic. The label on thecontainer should indicate the agent or compositions are used fortreating or prevention of one or more conditions of the disease. Thelabel can also indicate directions for administration and so on.

In addition to the container described above, a kit including apharmaceutical agent or compositions of the present invention canoptionally further include a second container housing apharmaceutically-acceptable diluent. It can further include othermaterials desirable from a commercial and user standpoint, includingother buffers, diluents, filters, needles, syringes, and package insertswith instructions for use.

The pharmaceutical compositions can, if desired, be presented in a packor dispenser device which can contain one or more unit dosage formscontaining the active ingredient. The pack can, for example, includemetal or plastic foil, such as a blister pack. The pack or dispenserdevice can be accompanied by instructions for administration.

(1) Pharmaceutical Agents or Compositions Containing the Peptides as theActive Ingredient

The peptides of this invention can be administered directly as apharmaceutical agent or compositions or if necessary, that has beenformulated by conventional formulation methods. In the latter case, inaddition to the peptides of this invention, carriers, excipients, andsuch that are ordinarily used for drugs can be included as appropriatewithout particular limitations. Examples of such carriers are sterilizedwater, physiological saline, phosphate buffer, culture fluid and such.Furthermore, the pharmaceutical agents or compositions can contain asnecessary, stabilizers, suspensions, preservatives, surfactants andsuch. The pharmaceutical agents or compositions of this invention can beused for anticancer purposes.

The peptides of this invention can be prepared as a combination,composed of two or more of peptides of the invention, to induce CTL invivo. The peptide combination can take the form of a cocktail or can beconjugated to each other using standard techniques. For example, thepeptides can be chemically linked or expressed as a single fusionpolypeptide sequence. The peptides in the combination can be the same ordifferent. By administering the peptides of this invention, the peptidesare presented at a high density by the HLA antigens on APCs, then CTLsthat specifically react toward the complex formed between the displayedpeptide and the HLA antigen are induced. Alternatively, APCs thatpresent any of the peptides of this invention on their cell surface areobtained by removing APCs (e.g., DCs) from the subjects, which arestimulated by the peptides of this invention, CTL is induced in thesubjects by read-ministering these APCs (e.g., DCs) to the subjects, andas a result, aggressiveness towards the cancer cells, such as bladdercancer, breast cancer, cholangiocellular carcinoma, esophageal cancer,non-small cell lung cancer (NSCLC), pancreatic cancer, prostate cancer,renal carcinoma and small cell lung cancer (SCLC) can be increased.

The pharmaceutical agents or compositions for the treatment and/orprevention of cancer, which include a peptide of this invention as theactive ingredient, can also include an adjuvant known to effectivelyestablish cellular immunity. Alternatively, they can be administeredwith other active ingredients, and they can be administered byformulation into granules. An adjuvant refers to a compound thatenhances the immune response against the protein when administeredtogether (or successively) with the protein having immunologicalactivity. Adjuvants contemplated herein include those described in theliterature (Clin Microbiol Rev 1994, 7: 277-89). Examples of suitableadjuvants include, but are not limited to, aluminum phosphate, aluminumhydroxide, alum, cholera toxin, salmonella toxin, and such, but are notlimited thereto.

Furthermore, liposome formulations, granular formulations in which thepeptide is bound to few-micrometers diameter beads, and formulations inwhich a lipid is bound to the peptide may be conveniently used.

In some embodiments, the pharmaceutical agents or compositions of theinvention may further include a component which primes CTL. Lipids havebeen identified as agents or compositions capable of priming CTL in vivoagainst viral antigens. For example, palmitic acid residues can beattached to the epsilon- and alpha-amino groups of a lysine residue andthen linked to a peptide of the invention. The lipidated peptide canthen be administered either directly in a micelle or particle,incorporated into a liposome, or emulsified in an adjuvant. As anotherexample of lipid priming of CTL responses, E. coli lipoproteins, such astripalmitoyl-S-glycerylcysteinlyseryl-serine (P3CSS) can be used toprime CTL when covalently attached to an appropriate peptide (see, e.g.,Deres et al., Nature 1989, 342: 561-4).

The method of administration can be oral, intradermal, subcutaneous,intravenous injection, or such, and systemic administration or localadministration to the vicinity of the targeted sites. The administrationcan be performed by single administration or boosted by multipleadministrations. The dose of the peptides of this invention can beadjusted appropriately according to the disease to be treated, age ofthe patient, weight, method of administration, and such, and isordinarily 0.001 mg to 1000 mg, for example, 0.001 mg to 1000 mg, forexample, 0.1 mg to 10 mg, and can be administered once in a few days tofew months. One skilled in the art can appropriately select a suitabledose.

(2) Pharmaceutical Agents or Compositions Containing Polynucleotides asthe Active Ingredient

The pharmaceutical agents or compositions of the invention can alsocontain nucleic acids encoding the peptides disclosed herein in anexpressible form. Herein, the phrase “in an expressible form” means thatthe polynucleotide, when introduced into a cell, will be expressed invivo as a polypeptide that induces anti-tumor immunity. In anexemplified embodiment, the nucleic acid sequence of the polynucleotideof interest includes regulatory elements necessary for expression of thepolynucleotide. The polynucleotide(s) can be equipped so to achievestable insertion into the genome of the target cell (see, e.g., Thomas KR & Capecchi M R, Cell 1987, 51: 503-12 for a description of homologousrecombination cassette vectors). See, e.g., Wolff et al., Science 1990,247: 1465-8; U.S. Pat. Nos. 5,580,859; 5,589,466; 5,804,566; 5,739,118;5,736,524; 5,679,647; and WO 98/04720. Examples of DNA-based deliverytechnologies include “naked DNA”, facilitated (bupivacaine, polymers,peptide-mediated) delivery, cationic lipid complexes, andparticle-mediated (“gene gun”) or pressure-mediated delivery (see, e.g.,U.S. Pat. No. 5,922,687).

The peptides of the present invention can also be expressed by viral orbacterial vectors. Examples of expression vectors include attenuatedviral hosts, such as vaccinia or fowlpox. This approach involves the useof vaccinia virus, e.g., as a vector to express nucleotide sequencesthat encode the peptide. Upon introduction into a host, the recombinantvaccinia virus expresses the immunogenic peptide, and thereby elicits animmune response. Vaccinia vectors and methods useful in immunizationprotocols are described in, e.g., U.S. Pat. No. 4,722,848. Examples ofanother vector include BCG (Bacille Calmette Guerin). BCG vectors aredescribed in Stover et al., Nature 1991, 351: 456-60. A wide variety ofother vectors useful for therapeutic administration or immunizatione.g., adeno and adeno-associated virus vectors, retroviral vectors,Salmonella typhi vectors, detoxified anthrax toxin vectors, and thelike, will be apparent. See, e.g., Shata et al., Mol Med Today 2000, 6:66-71; Shedlock et al., J Leukoc Biol 2000, 68: 793-806; Hipp et al., InVivo 2000, 14: 571-85.

Delivery of a polynucleotide into a subject can be either direct, inwhich case the subject is directly exposed to a polynucleotide-carryingvector, or indirect, in which case, cells are first transformed with thepolynucleotide of interest in vitro, then the cells are transplantedinto the subject. Theses two approaches are known, respectively, as invivo and ex vivo gene therapies.

For general reviews of the methods of gene therapy, see Goldspiel etal., Clinical Pharmacy 1993, 12: 488-505; Wu and Wu, Biotherapy 1991, 3:87-95; Tolstoshev, Ann Rev Pharmacol Toxicol 1993, 33: 573-96; Mulligan,Science 1993, 260: 926-32; Morgan & Anderson, Ann Rev Biochem 1993, 62:191-217; Trends in Biotechnology 1993, 11(5): 155-215). Methods commonlyknown in the art of recombinant DNA technology which can also be usedfor the present invention are described in eds. Ausubel et al., CurrentProtocols in Molecular Biology, John Wiley & Sons, NY, 1993; andKrieger, Gene Transfer and Expression, A Laboratory Manual, StocktonPress, NY, 1990.

The method of administration can be oral, intradermal, subcutaneous,intravenous injection, or such, and systemic administration or localadministration to the vicinity of the targeted sites finds use. Theadministration can be performed by single administration or boosted bymultiple administrations. The dose of the polynucleotide in the suitablecarrier or cells transformed with the polynucleotide encoding thepeptides of this invention can be adjusted appropriately according tothe disease to be treated, age of the patient, weight, method ofadministration, and such, and is ordinarily 0.001 mg to 1000 mg, forexample, 0.001 mg to 1000 mg, for example, 0.1 mg to 10 mg, and can beadministered once every a few days to once every few months. One skilledin the art can appropriately select the suitable dose.

X. METHODS USING THE PEPTIDES, EXOSOMES, APCS AND CTLS

The peptides of the present invention and polynucleotides encoding suchpeptides can be used for inducing APCs and CTLs. The exosomes and APCsof the present invention can be also used for inducing CTLs. Thepeptides, polynucleotides, exosomes and APCs can be used in combinationwith any other compounds so long as the compounds do not inhibit theirCTL inducibility. Thus, any of the aforementioned pharmaceutical agentsor compositions of the present invention can be used for inducing CTLs,and in addition thereto, those including the peptides andpolynucleotides can be also be used for inducing APCs as discussedbelow.

(1) Method of Inducing Antigen-Presenting Cells (APCs)

The present invention provides methods of inducing APCs using thepeptides of this invention or polynucleotides encoding the peptides. Theinduction of APCs can be performed as described above in section “VI.Antigen-presenting cells”. This invention also provides a method forinducing APCs having a high level of CTL inducibility, the induction ofwhich has been also mentioned under the item of “VI. Antigen-presentingcells”, supra.

Preferably, the methods for inducing APCs include at least one stepselected from among:

a: contacting APCs with the peptides of the present invention, and

b: introducing the polypeptides of the present invention in anexpressible form into APCs.

Such methods for inducing APCs are preferably performed in vitro or exvivo. When the methods performed in vitro or ex vivo, APCs to be inducedmay be obtained from a subject to be treated or others whose HLAantigens are the same as the subject. In preferred embodiment, the APCsinduced by the present methods carry HLA-A2 antigen, in particularHLA-A2 (A*0201) on its surface.

(2) Method of Inducing CTLs

Furthermore, the present invention provides methods for inducing CTLsusing the peptides of this invention, polynucleotides encoding thepeptides, or exosomes or APCs presenting the peptides.

The present invention also provides methods for inducing CTLs using apolynucleotide encoding a polypeptide that is capable of forming a Tcell receptor (TCR) subunit recognizing (i.e., binding to) a complex ofthe peptides of the present invention and HLA antigens on a cellsurface. Preferably, the methods for inducing CTLs include at least onestep selected from among:

a: contacting a CD8-positive T cell with an antigen-presenting celland/or an exosome that presents on its surface a complex of an HLAantigen and a peptide of the present invention, and

b: introducing a polynucleotide encoding a polypeptide that is capableof forming a TCR subunit recognizing a complex of a peptide of thepresent invention and an HLA antigen into a CD8 positive T cell.

When the peptides of this invention are administered to a subject, CTLis induced in the body of the subject, and the strength of the immuneresponse targeting the tumor-associated endothelia is enhanced.Alternatively, the peptides and polynucleotides encoding the peptidescan be used for an ex vivo therapeutic method, in which subject-derivedAPCs, and CD8-positive cells, or peripheral blood mononuclear leukocytesare contacted (stimulated) with the peptides of this invention in vitro,and after inducing CTL, the activated CTL cells are returned to thesubject. For example, the method can include steps of:

a: collecting APCs from subject,

b: contacting with the APCs of step a, with the peptide,

c: mixing the APCs of step b with CD⁸⁺ T cells, and co-culturing forinducing CTLs, and

d: collecting CD⁸⁺ T cells from the co-culture of step c.

Alternatively, according to the present invention, use of the peptidesof this invention for manufacturing a pharmaceutical compositioninducing CTLs is provided. In addition, the present invention provides amethod or process for manufacturing a pharmaceutical agent orcomposition inducing CTLs, wherein the method comprises the step ofadmixing or formulating the peptide of the present invention with apharmaceutically acceptable carrier. Further, the present invention alsoprovides the peptide of the present invention for inducing CTLs.

The CD8⁺ T cells having cytotoxic activity obtained by step d can beadministered to the subject as a vaccine. The APCs to be mixed with theCD8⁺ T cells in above step c can also be prepared by transferring genescoding for the present peptides into the APCs as detailed above insection “VI. Antigen-presenting cells”; but are not limited thereto andany APC or exosome which effectively presents the present peptides tothe T cells can be used for the present method.

Although methods and materials similar or equivalent to those describedherein can be used in the practice or testing of the present invention,suitable methods and materials are described. All publications, patentapplications, patents, and other references mentioned herein areincorporated by reference in their entirety. In case of conflict, thepresent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and notintended to be limiting.

The following examples are presented to illustrate the present inventionand to assist one of ordinary skill in making and using the same. Theexamples are not intended in any way to otherwise limit the scope of theinvention.

EXAMPLES Materials and Methods

cDNA Microarray Analysis

A profiling of the gene expression by a cDNA microarray analysis wasdone as described previously (Nakamura T, et al. Oncogene 2004;23:2385-400). The tissue samples from pancreatic cancers and adjacentnoncancerous normal pancreatic tissues were obtained from surgicalspecimens, and all patients provided their written informed consent toparticipate in this study. In FIG. 1C, the relative expression ratio wascalculated by dividing the value of the expression of RAB6KIFL mRNA incancer cells by that in normal counterpart. In FIG. 1B, the relativeexpression ratio of normal tissues was calculated by dividing the valueof the expression of RAB6KIFL mRNA in each normal tissue by the value ofthe expression of RAB6KIFL mRNA in control RNA that was a mixture ofequal amount of RNA samples from 40 normal tissues indicated in FIG. 1B.

Mice

HLA-A2.1 (HHD) Tgm; H-2 D^(b−/−) beta 2 m^(−/−) double knockout miceintroduced with a human beta 2m-HLA-A2.1 (alpha 1, alpha 2)-H-2 D^(b)(alpha 3 transmembrane cytoplasmic; HHD) monochain construct gene weregenerated in the Department SIDA-Retrovirus, Unite d'Immunite CellulaireAntivirale, Institute Pasteur, France (Pascolo S, et al. J Exp Med 1997;185:2043-51, Firat H, et al. Eur J Immunol 1999; 29:3112-21) and kindlyprovided by Dr. F. A. Lemonnier. The mice were maintained at the Centerfor Animal Resources and Development of Kumamoto University and theywere handled in accordance with the animal care guidelines of KumamotoUniversity.

Cell Lines and HLA-Expression

The human pancreatic cancer cell line PANC1, human colon cancer cellline CaCo-2, and a TAP-deficient and HLA-A2 (A*0201)-positive cell lineT2 were purchased from Riken Cell Bank (Tsukuba, Japan). The humanpancreatic cancer cell line PK8 was kindly provided by the Cell ResourceCenter for Biomedical Research Institute of Development, Aging andCancer, Tohoku University (Sendai, Japan). The human liver cancer cellline SKHep1 was kindly provided by Dr. Kyogo Ito, Kurume University(Kurume, Japan). The expression of HLA-A2 was examined using flowcytometry with an anti-HLA-A2 monoclonal antibody (mAb), BB7.2 (OneLambda, Inc., Canoga Park, Calif.) in order to select theHLA-A2-positive blood donors and target cell lines for the cytotoxicityassays. These cells were maintained in vitro in RPMI 1640 or DMEM mediumsupplemented with 10% FCS in a 5% CO₂ atmosphere at 37 degrees C.

Patients, Blood Samples, and Tumor Tissues.

The clinical research using PBMCs from the donors was approved by theInstitutional Review Board of Kumamoto University, Kumamoto, Japan. Theblood samples and the cancer and adjacent non-cancerous tissues wereobtained during routine diagnostic procedures after obtaining formalwritten informed consents by the patients in Kumamoto UniversityHospital. Blood samples were also obtained from healthy donors afterreceiving their written informed consent. All samples were anonymous,numbered at random, and stored at −80 degrees C. until use. All patientsand healthy donors were of Japanese nationality.

Reverse Transcription-PCR and Northern Blot Analysis.

Reverse transcription-PCR(RT-PCR) analysis of normal and cancer tissuesand cell lines was done to evaluate the expression of RAB6KIFL at mRNAlevel. The primer sequences were as follows: RAB6KIFL, sense5′-CTACAAGCACCCAAGGACTCT-3′ (SEQ ID NO: 6) and antisense5′-AGATGGAGAAGCGAATGTTT-3′ (SEQ ID NO: 7) and beta-actin, sense5′-CATCCACGAAACTACCTTCAACT-3′ (SEQ ID NO: 8) and antisense5′-TCTCCTTAGAGAGAAGTGGGGTG-3′ (SEQ ID NO: 9), and used RT-PCR reactionsconsisting of initial denaturation at 94 degrees C. for 5 minutes and32-35 amplification cycles at an annealing temperature of 58 degrees C.After normalization by beta-actin mRNA as a control, the expression ofRAB6KIFL mRNA was compared in tissues and cell lines.

Western Blot Analysis and Immunohistochemical Examination.

Western blotting and immunohistochemical staining of RAB6KIFL proteinwere performed as described previously (Nakatsura T, et al. BiochemBiophys Res Commun 2001; 281:936-44. Yoshitake Y, et al. Clin Cancer Res2004; 10:6437-48.). For Western blotting analyses of human normaltissues, a pre-made human adult normal tissue blot (Biochain, Hayward,Calif.) was used. The primary antibodies used herein, anti-RAB6KIFLpolyclonal antibody, and monoclonal anti-b-actin antibody, werepurchased from Bethyl Laboratories, Inc. (Montgomery, Tex., USA) andSigma (Steinheim, Germany), respectively. Immunohistochemical stainingof CD4 or CD8 in tissue specimens of HLA-A2.1 (HHD) Tgm immunized withthe RAB6KIFL-A2-10-284 peptide was done as described previously(Matsuyoshi H, et al. 2004; 172:776-86).

Lentiviral Gene Transfer

A lentiviral vector-mediated gene transfer was performed as describedpreviously (Imai K, et al. Clin Cancer Res 2008; 14:6487-95,Tahara-Hanaoka S, et al. Exp Hematol 2002; 30:11-7). Briefly, 17 micro-gof CSII-CMV-RfA and CSIIEF-RfA self-inactivating vectors (Miyoshi H, etal. J Virol 1998; 72: 8150-7) carrying RAB6KIFL cDNAs and 10 micro-g ofpCMV-VSV-G-RSV-Rev and pCAG-HIV gp were transfected into the 293T cellsgrown in a 10-cm culture dish using Lipofectamine 2000 reagent(Invitrogen Corporation, Carlsbad, Calif., USA). After 60 hr oftransfection, the medium was recovered and the viral particles werepelleted by ultra-centrifugation (50,000×g, 2 hr). The pellet wassuspended in 50 micro-L of RPMI 1640 medium and 10 micro-L of viralsuspension was added to 5×10⁴ SKHep1 cells, per well in a flat-bottom96-well plate. The expression of the transfected RAB6KIFL gene wasconfirmed by a Western blot analysis.

Induction of RAB6KIFL-Reactive Mouse CTLs and IFN-Gamma Enzyme-LinkedImmunospot Assay.

Human RAB6KIFL-derived peptides (purity>95%), carrying binding motifsfor HLA-A2 (A*0201)-encoded molecules, were selected using the BIMASsoftware program (BioInformatics and Molecular Analysis Section, Centerfor information Technology, NIH, Bethesda, Md.) and 36 peptides weresynthesized (American Peptide Company, CA, USA). HLA-A2-restricted HIVpeptide (SLYNTYATL) (SEQ ID NO: 10) was used as an irrelevant peptide.The immunization of the mice with peptides was done as previouslydescribed (Nakatsura T, et al. Biochem Biophys Res Commun 2003;306:16-25). The frequency of cells producing IFN-gamma/1×10⁵ CD4-spleencells upon stimulation with syngeneic BM-DC (1×10⁴/well) pulsed with orwithout each peptide was analyzed by an enzyme-linked immunospot(ELISPOT) assay as previously described (Komori H, et al. Clin CancerRes 2006; 12: 2689-97).

Induction of RAB6KIFL-reactive human CTLs.

Human RAB6KIFL-derived peptides (purity>95%), carrying binding motifsfor HLA-A2 (A*0201)-encoded molecules, were selected using the BIMASsoftware program (BioInformatics and Molecular Analysis Section, Centerfor Information Technology, NIH, Bethesda, Md.) and 36 peptides weresynthesized (American Peptide Company, CA, USA) (Tables 1A and B).Monocyte-derived DCs were used as antigen-presenting cells to induce CTLresponses against peptides presented in the context of HLA. DCs weregenerated in vitro culture as described previously (Yoshitake Y, et al.Clin Cancer Res 2004; 10:6437-48, Harao M, et al. Int J Cancer 2008; inpress., Imai K, et al. Clin Cancer Res 2008; in press.). Briefly, PBMCsisolated from a normal volunteer positive for HLA-A2 using Ficoll-Plaque(GE Healthcare UK, Ltd., Buckinghamshire, UK) solution were sorted toCD8⁺ population and CD14⁺ population with microbeads (Miltenyi Biotec,Bergisch Gladbach, Germany). To generate DCs, the CD14⁺ population wascultured in the presence of 100 ng/mL granulocyte-macrophagecolony-stimulating factor (GM-CSF; PeproTec Inc., NJ, USA) and 10 ng/mLinterleukin (IL)-4 (PeproTec) in AIM-V (Invitrogen) containing 2%heat-inactivated autologous plasma. After 5 days of culture, OK-432 wasadded into the dish to make the DCs mature. At seven days after startingto culture the cytokine-generated DCs, they were pulsed with 20 ng/mLHLA-A2-binding peptides in the presence of 4 micro g/mL beta2-microglobulin (Sigma-Aldrich, St. Louis, Mo., USA) for 2 h at 37degrees C. in AIM-V. These peptides pulsed DCs were then irradiated (40Gy) and mixed at a 1:50 ratio with autologous CD8⁺ T cells, obtained bypositive selection of PBMCs with anti-CD8 microbeads (Miltenyi Biotec).These cultures were set up in 24-well plates, each well contained 1×10⁵peptide-pulsed DCs, 2×10⁶ CD8⁺ T cells and 5 ng/mL human recombinantIL-7 (Wako, Osaka, Japan) in 2 mL AIM-V with 2% autologous plasma. After2 days, these cultures were supplemented with human recombinant IL-2(PeproTec Inc.) to a final concentration of 20 IU/mL. Two additionalweekly stimulations with peptide-loaded autologous DCs using the sameprocedure were carried out on day 7 and 14. Six days after the laststimulation, the antigen-specific responses of induced CTLs wereinvestigated by ⁵¹Cr release assay and IFN-gamma ELISPOT assay.

CTL Responses Against Cancer Cell Lines.

The CTLs were cocultured with each of the cancer cells, or thepeptide-pulsed T2 cells, as a target cell (5×10³/well) at the indicatedeffector/target ratio and a standard ⁵¹Cr release assay was done asdescribed previously (Yoshitake Y, et al. Clin Cancer Res 2004;10:6437-48. Imai K, et al. Clin Cancer Res 2008; in press.). Briefly,target cells were labeled with 3.7 KBq Na₂ ⁵¹Cr⁴ (Perkin Elmer LifeSciences) for 1 h at 37 degree C. in a CO₂ incubator. Labeled targetcells were rinsed three times, and peptide-pulsed target cells wereprepared by incubating the cells with 20 micro g/mL peptide for 3 h at37 degrees C. Target cells were mixed with effector cells in finalvolume of 200 micro L in flat-bottomed microtiter plates and incubated.After 6 h incubation, 50 micro L of the supernatant was collected fromeach well and the radioactivity was quantified using a gamma counter.The specific cytotoxicity was evaluated by calculating the percentage ofspecific ⁵¹Cr release.

The blocking of HLA-class I, or HLA-DR, was done as described previously(Yoshitake Y, et al. Clin Cancer Res 2004; 10:6437-48, Imai K, et al.Clin Cancer Res 2008; in press.). In brief, before the coculture of theCTLs with a cancer cell line in the ⁵¹Cr release assay or ELISPOT assay,the target cancer cells were incubated for 1 hour with 10 micro g/mLanti-class I mAb, W6/32, or 10 micro g/mL anti-HLA-DR mAb, H-DR-1, andthen the effects of the mAbs on either the cytotoxic activity or theproduction of IFN-gamma by the CTLs were examined.

Statistical Analysis.

The two-tailed Student's t-test was used to evaluate the statisticalsignificance of differences in the data obtained by the ELISPOT assayand in the tumor size between the treatment groups. A value of P<0.05was considered to be significant. The statistical analysis was performedusing a commercial statistical software package (SPSS for Windows,version 11.0, Chicago, Ill., USA).

Results

Identification of RAB6KIFL Gene Up-Regulated in Pancreatic Cancer andVarious Malignancies Based on a cDNA Microarray.

Using a genome-wide cDNA microarray containing 27,648 genes, the geneexpression profiles of 6 pancreatic cancer tissues and their adjacentnormal counterparts had been previously examined. After the analysis, 6genes were chosen. Because the relative expression ratio of these geneswas more than five times higher in pancreatic cancer tissues incomparison to their normal counterparts (FIG. 1A) (Imai K, et al. ClinCancer Res 2008; 14: 6487-95). The expression of these genes wasanalyzed using a cDNA microarray analysis in 29 kinds of normal tissuesincluding 4 embryonic tissues (FIG. 1B). Consequently, RAB6KIFL/KIF20Awas focused as a novel TAA of pancreatic cancer. The expression of theRAB6KIFL gene in pancreatic cancer tissues was markedly enhanced in allof the 6 patients tested (the average of the relative expression ratio:32,000, range: 15-72,000). In addition, the RAB6KIFL gene was faintlyexpressed only in testis and thymus (FIG. 1B). The expression level ofthe RAB6KIFL gene was also enhanced in lung and bladder cancers based onthe previous cDNA microarray analysis (FIG. 1C) (Nakamura T, et al.Oncogene 2004; 23:2385-400, Kitaharai 0, et al. Cancer Res 2001; 61:3544-9, Hasegawa S, et al. Cancer Res 2002; 62: 7012-7, Kikuchi T, etal. Oncogene 2003; 22: 2192-205, Obama K, et al. Hepatology 2005; 41:1339-48).

Expression of RAB6KIFL mRNA and Protein in Normal Organs, Cancer CellLines, and Pancreatic Cancer Tissues.

The expression of the RAB6KIFL gene in normal tissues at the mRNA levelwas analyzed using RT-PCR analysis. A semiquantitative RT-PCR analysisof RAB6KIFL in the normal tissues revealed that it was expressed only intestis (FIG. 2A). The expression of the RAB6KIFL gene was detected inthe almost all pancreatic and other HLA-A2-positive cancer cell linesusing an RT-PCR analysis (FIG. 2B).

Subsequently, the expression of the RAB6KIFL gene was analyzed using anRT-PCR analysis in the pancreatic cancer tissues and their adjacentnormal counterparts, which were surgically resected. The expression ofthe RAB6KIFL gene was detected in 5 of 8 pancreatic cancer tissues, butlittle expression was detected in their normal counterparts (FIG. 2C).In addition, its expression was detected in the metastatic foci of theskin and peritoneum.

The expression of RAB6KIFL protein in cancerous and several normaltissues were also examined by Western blotting (FIGS. 3A, B). RAB6KIFLprotein could not be detected in eight normal tissues and testis gave avery faint band that had similar mobility with that observed in a lysateof PANC1 cells (FIG. 3A). On the other hand, RAB6KIFL protein wasdetected in pancreatic cancer tissues of two patients examined but notin the adjacent normal tissues (FIG. 3B).

To confirm the tumor-associated overexpression of RAB6KIFL protein, manyparaffin-embedded pancreatic cancer tissue specimens were then examinedby immunohistochemical analyses. Strong staining of RAB6KIFL was mainlyobserved at the cytoplasm of cancer cells in pancreatic cancer, whereasvery weak staining was observed in aciner cells and normal ductalepithelium of their normal adjacent pancreatic tissues (FIG. 4A). Inaddition, similar strong staining was observed in the metastatic foci ofperitoneum (FIG. 4A). No staining was detected in the tissue specimensof tumor-forming pancreatitis (FIG. 4A). RAB6KIFL was not stained in thenormal brain, lung, liver, kidney, stomach, small intestine, colon,spleen, skeletal muscle, skin, thymus and testis (FIG. 4B).

Prediction of HLA-A2 (A*0201) Binding Peptides Derived from RAB6KIFL

Table 1A and B show HLA-A2 (A*0201) binding peptides of the RAB6KIFLprotein in the order of score of prediction high binding affinity. Intotal, 36 peptides with potential HLA-A2 binding activity were selected.

TABLE 1A HLA-A2 (A*0201) binding 9mer peptides derived from RAB6KIFLstart Designation position Subsequence Score SEQ ID 204 LLSNEVIWL 459RAB6KIFL-A2-9-12 12 LLSDDDVVV 199 SEQ ID NO: 3 715 KMLEPPPSA 191 750KLGESLQSA 164 300 SIWISFFEI 131 38 NLLSDCSVV 106 688 QLQEVKAKL 88 695KLQQCKAEL 75 RAB6KIFL-A2-9-809 809 CIAEQYHTV 59 SEQ ID NO: 4 11GLLSDDDVV 52 436 TLGRCIAAL 49 179 ILPRSLALI 41 183 SLALIFNSL 41 625KLNILKESL 37 781 ILIKQDQTL 36 231 GLQEEELST 31 494 TLHVAKFSA 29 556SMYGKEELL 24 788 TLAELQNNM 20 209 VIWLDSKQI 20 Start position indicatesthe number of amino acid from the N-terminus of RAB6KIFL. Binding scoreis derived in Materials and Methods.

TABLE 1B HLA-A2 (A*0201) binding 10mer peptides derived from RAB6KIFLstart Designation position Subsequence Score SEQ ID 654 LLQEARQQSV 485788 TLAELQNNMV 285 742 RLLRTELQKL 182 39 LLSDCSVVST 119 11 GLLSDDDVVV106 400 KISELSLCDL 97 573 LLLKERQEKL 66 97 VLQAPKDSFA 46RAB6KIFL-A2-10-284 284 AQPDTAPLPV 29 SEQ ID NO: 5 132 GQASFFNLTV 27 625KLNILKESLT 26 382 SIFSIRILHL 25 203 PLLSNEVIWL 22 455 NLVPFRDSKL 21 506QLVHAPPMQL 21 98 LQAPKDSFAL 21 66 KVYLRVRPLL 21 Start position indicatesthe number of amino acid from the N-terminus of RAB6KIFL. Binding scoreis derived in Materials and Methods.

Identification of RAB6KIFL-Derived and HLA-A2-Restricted Mouse CTLEpitopes Using HLA-A2.1 (HHD) Transgenic Mice

To identify the RAB6KIFL-derived and HLA-A2-restricted CTL epitopes, 36different candidate peptides were selected. Each consisted of 9 or 10amino-acids that have high predicted binding scores to HLA-A2 (A*0201),the most common HLA-allelic product worldwide, based on the HLA peptidebinding prediction algorism provided by the NIH BIMAS (Tables 1A, B). Todetermine which could induce peptide-reactive CTLs, the CD4⁻ spleencells isolated from HLA-A2.1 (HHD) Tgm, immunized i.p. twice with BM-DCspulsed with the twelve sets of the mixture of three kinds of peptidesselected from these 36 peptides, were again stimulated in vitro withBM-DCs pulsed with each peptide. The results showed that the CD4⁻ spleencells, stimulated with RAB6KIFL-A2-9-12, RAB6KIFL-A2-9-809, andRAB6KIFL-A2-10-284 peptide, produced a significant amount of IFN-gammain a peptide-specific manner in an ELISPOT assay (FIG. 5A). These CD4⁻spleen cells (2×10⁴) showed 149.0 plus/minus 22.2 spot counts/well inresponse to the BM-DCs pulsed with the RAB6KIFL-A2-9-12 peptide, whereasthey showed 32.6 plus/minus 9.9 spot counts/well in the presence of theBM-DCs without peptide loading (P<0.01). Likewise, the CD4⁻ spleen cellsstimulated with BM-DCs pulsed with RAB6KIFL-A2-9-809 peptide showed117.2 plus/minus 23.4 spot counts/well, whereas they showed 51.4plus/minus 7.8 spot counts/well in the presence of BM-DCs withoutpeptide loading (P<0.01). Moreover, the CD4⁻ spleen cells stimulatedwith BM-DCs pulsed with RAB6KIFL-A2-10-284 peptide also showed 141.2plus/minus 5.5 spot counts/well, whereas they showed 19.2 plus/minus 5.2spot counts/well in the presence of BM-DCs without peptide loading(P<0.01). No significant peptide-specific response was observed with theother peptides. These results suggest that the RAB6KIFL-A2-9-12,RAB6KIFL-A2-9-809 and RAB6KIFL-A2-10-284 peptides could be the HLA-A2restricted CTL epitope peptides in the HLA-A2.1 (HHD) Tgm, and thosepeptides were expected to be epitopes for human CTLs.

No Autoimmune Phenomenon Induced by the Immunization with EpitopePeptide, RAB6KIFL-A2-9-809, in HLA-A2.1 (HHD) Tgm

It is very important to investigate whether the immunization withRAB6KIFL peptide induce an autoimmune reaction or not. We thus performedthe immunohistochemical analysis of several vital organs with anti-CD4and anti-CD8 mAb in HLA-A2 (HHD) Tgm after two-times vaccination withRAB6KIFL-A2-9-809 peptide, of which amino-acid sequences were completelyconserved between human and mouse RAB6KIFL. As a result, no pathologicchange, such as lymphocyte infiltration or tissue destruction suggestingautoimmunity was observed (FIG. 5B). The abnormalities frequentlyobserved in mice affected with autoimmune diseases such as abnormal hairand skin, diarrhea and weight loss were also not observed in these mice.These results indicate that lymphocytes stimulated withRAB6KIFL-A2-9-809 peptide did not attack the normal tissues at least inHLA-A2 Tgm.

Induction of RAB6KIFL-Reactive CTLs from PBMCs of HLA-A2(A*0201)-Positive Healthy Donors

The generation of RAB6KIFL-specific CTLs was attempted from the PBMCs ofhealthy donors positive for HLA-A2 (A*0201) by the stimulation with theRAB6KIFL-A2-9-12 (SEQ ID NO: 3), RAB6KIFL-A2-9-809 (SEQ ID NO: 4) andRAB6KIFL-A2-10-284 (SEQ ID NO: 5) peptides. PBMCs were isolated formHLA-A2-positive healthy donors, and the CD8⁺ T cells sorted from thePBMCs were incubated with the autologous monocyte-derived DCs pulsedwith each peptide. After three times stimulations, the cytotoxicactivity against the peptide-pulsed T2 cells was examined by a ⁵¹Crrelease assay (FIG. 6A) and an IFN-gamma ELISPOT assay (data not shown).The CTLs induced from the PBMCs of two healthy donors exhibitedcytotoxic activity to the T2 cells pulsed with RAB6KIFL-A2-9-12 (SEQ IDNO: 3), RAB6KIFL-A2-9-809 (SEQ ID NO: 4) or RAB6KIFL-A2-10-284 (SEQ IDNO: 5) peptide, but not to the T2 cells pulsed with irrelevant andHLA-A2-restricted HIV peptide, or without peptide loading. Similarresponses were observed in other donors (data not shown). These resultsindicate that these CTLs had a peptide-specific cytotoxicity.

Subsequently, it was investigated whether these CTLs were able to killhuman cancer cell lines expressing RAB6KIFL and HLA-A2 (A*0201). Asshown in FIG. 6B, the RAB6KIFL-reactive CTLs stimulated withRAB6KIFL-A2-9-12 (left), RAB6KIFL-A2-9-809 (middle), orRAB6KIFL-A2-10-284 (right) peptide exhibited cytotoxicity to PANC1(RAB6KIFL⁺, HLA-A2⁺), CaCo-2 (RAB6KIFL HLA-A2⁺), but not to PK8(RAB6KIFL⁺, HLA-A2⁻) in healthy donors.

Furthermore, SKHep1/RAB6KIFL (RAB6KIFL^(high), HLA-A2⁺), the SKHep1(RAB6KIFL^(low), HLA-A2⁺) cells transfected with the RAB6KIFL gene (FIG.2B), were used as target cells to confirm that these peptides wereprocessed naturally from the RAB6KIFL protein in the cancer cells. Asshown in FIG. 6C, the CTLs induced by stimulation with RAB6KIFL-A2-9-12(left), RAB6KIFL-A2-9-809 (middle), and RAB6KIFL-A2-10-284 (right)peptide exhibited cytotoxicity against SKHep1/RAB6KIFL, but not againstSKHep1/Mock. These results suggest that these peptides could benaturally processed and expressed on the surface of cancer cells in thecontext of HLA-A2 molecules.

To confirm that the induced CTLs recognized the target cells in anHLA-class I-restricted manner, an HLA-class I blocking assay wasperformed by using the mAb against HLA-class T (W6/32) was used to blockthe recognition of cancer cells by the CTLs (FIG. 6D). As a result, theanti-HLA-class I antibody could markedly inhibit the IFN-gammaproduction stimulated with PANC1 cells in an ELISPOT assay of the CTLsgenerated by stimulation with RAB6KIFL-A2-9-12 (left), RAB6KIFL-A2-9-809(middle), or RAB6KIFL-A2-10-284 (right) peptide, with statisticalsignificance (FIG. 6D, P<0.01). These results clearly indicate thatthese induced CTLs recognized the target cells expressing RAB6KIFL in anHLA-class I-restricted manner.

Discussion

According to the example, it was shown that RAB6KIFL is a TAA as apromising target of anticancer immunotherapy for pancreatic cancer. Toestablish anticancer immunotherapy, it is important to identify the TAAsthat are strongly expressed in tumor cells but not in the normal cells.The cDNA microarray analysis showed that RAB6KIFL mRNA was overexpressedin pancreatic cancer cells (Imai K, Hirata S, Irie A, Senju S, Ikuta Y,Yokomine K, Harao M, Inoue M, Tsunoda T, Nakatsuru S, Nakagawa H,Nakamura Y, et al. Clin Cancer Res 2008; 14: 6487-95) and barelyexpressed in their normal counterparts and many normal adult tissuesexcept for the testis and thymus (FIG. 1B). In addition, the RAB6KIFLgene was also overexpressed in lung and bladder cancers as well as inpancreatic cancer (FIG. 1C). In the RT-PCR analysis demonstrated thatRAB6KIFL mRNA was frequently expressed in several cancer cell lines andpancreatic cancer tissues, but not in adult normal tissues includingbone marrow except for testis (FIG. 2). Similarly, Western blottinganalyses and immunohistochemical analyses revealed that RAB6KIFL proteinwas detected in pancreatic cancer cells, but not in their normalcounterparts and normal adult tissues including thymus except for testis(FIGS. 3, 4). These observations support a characteristic of RAB6KIFL asa cancer testis-like TAA at a protein level.

For the identification of TAAs as useful targets for anticancerimmunotherapy, another key point is to select the antigens which areindispensable for the proliferation, invasion, metastasis, and survivalof cancer cells. Recently, Taniuchi et al. reported that RAB6KIFL isinvolved in pancreatic carcinogenesis (Taniuchi K, et al. Cancer Res2005; 65:105-12), in addition to its previously described role inmembrane traffic (Echard A, et al. Science 1998; 279:580-5) andcytokinesis (Fontijn R D, et al. Mol Cell Biol 2001; 21:2944-55, Hill E,Clarke M, Barr F A. EMBO J. 2000; 19:5711-9). They showed that thedown-regulation of endogenous RAB6KIFL in pancreatic cancer cells bysmall interfering RNA results in a drastic attenuation of cancer cellgrowth through the interaction with disc, large homologue 5 (DLG5), acargo protein of RAB6KIFL (Taniuchi K, et al. Cancer Res 2005;65:105-12), suggesting that RAB6KIFL thus appears to play a criticalrole in pancreatic carcinogenesis and would therefore be a potentiallyuseful target of anticancer immunotherapy.

The potential of RAB6KIFL as an immunotherapeutic target was verifiedherein by identifying the HLA-A2-restricted epitope peptides andevaluating their immunogenicity. The experiment using HLA-A2 (HHD) Tgmidentified three HLA-A2-restricted RAB6KIFL epitope peptides which couldstimulate the generation of HLA-A2-restricted mouse CTLs by thevaccination with the 36 candidate peptides predicted to have bindingaffinity to HLA-A2 (A*0201) by the BIMAS algorithm, without causingautoimmune phenomenon such as lymphocyte infiltration or tissuedestruction (FIG. 5). Furthermore, the RAB6KIFL-reactive CTLs could begenerated from PBMCs stimulated with all of these three peptides inthree independent healthy donors (FIG. 6). These CTLs could kill notonly the T2 cells pulsed with its cognate peptide, but also the cancercell lines expressing both RAB6KIFL and HLA-A2. The antigen-specificityof CTLs to these peptides was confirmed by the findings that these CTLsexhibited cytotoxicity to SKHep1 cells transfected with human RAB6KIFLgene, but not to the mock-transfected SKHep1. These data suggest thatthese RAB6KIFL peptides (RAB6KIFL-A2-9-12, RAB6KIFL-A2-9-809, andRAB6KIFL-A2-10-284) are naturally processed from RAB6KIFL protein incancer cells and presented onto the cell surface together with HLA-A2molecules to be recognized by the CTLs. In addition, it would bepossible that the RAB6KIFL-A2-9-809 peptide can be more effectivelyprocessed from RAB6KIFL protein in comparison to the RAB6KIFL-A2-9-12and RAB6KIFL-A2-10-284 peptides in cancer cells, because theRAB6KIFL-A2-9-809 peptide-induced CTLs exhibited stronger cytotoxicitydirected against cancer cells expressing both RAB6KIFL and HLA-A2 incomparison to cytotoxicity mediated by CTLs induced by stimulation withthe RAB6KIFL-A2-9-12 or the RAB6KIFL-A2-10-284 peptides.

HLA-A2.1 (HHD) Tgm that lacked expression of endogenous mouseH-2^(b)-encoded class I molecules were used to identifyHLA-A2-restricted CTL epitope peptides of RAB6KIFL. HLA-A2.1 (HHD) Tgmwas reported to be a versatile animal model for the preclinicalevaluation of peptide-based immunotherapy (Imai K, et al. Clin CancerRes 2008; 14:6487-95, Komori H, et al. Clin Cancer Res 2006; 12:2689-97,Harao M, et al. Int J Cancer 2008; 123: 2616-25, Pascolo S, et al. J ExpMed 1997; 185: 2043-51, Firat H, et al. Eur J Immunol 1999; 29:3112-21).

To avoid the adverse effects induced by vaccination of TAAs, RAB6KIFLwas selected as a target which was barely expressed in adult normaltissues. However, it was very important to determine whether vaccinationof RAB6KIFL could induce autoimmune diseases either during or afteranticancer immunotherapy. Herein, the amino-acid sequences of two ofthree epitope peptides are not conserved between human and mouse(RAB6KIFL-A2-9-12, human: LLSDDDVVV (SEQ ID NO: 3), mouse: LLSDEDVVD(SEQ ID NO: 11); RAB6KIFL-A2-10-284, human: AQPDTAPLPV (SEQ ID NO: 5),mouse: AQPDTVPVSV) (SEQ ID NO: 12). Therefore, the autoimmune phenomenonin HLA-A2 Tgm was investigated after two-times vaccination withRAB6KIFL-A2-9-809 peptide in which amino-acid sequences were completelyconserved between in human and mouse. One of the advantages of usingHLA-A2 Tgm is that the possibility of autoimmune phenomenon could beinvestigated in vivo. Of course, because the number of normal tissuesinvestigated herein is limited, it is not possible to exclude thepossible expression of RAB6KIFL in some normal tissues that has not beeninvestigated herein. Therefore, it must be careful about induction ofautoimmune diseases when utilizing RAB6KIFL peptides for cancerimmunotherapy.

In conclusion, the current results suggest that RAB6KIFL is a TAAcontaining epitope peptides that can elicit CTLs reactive to cancercells expressing both RAB6KIFL and HLA-A2. Since RAB6KIFL is highlyexpressed in a wide range of human malignancies, RAB6KIFL is therefore apromising target for peptide-based immunotherapy for the treatment of abroad-spectrum of malignancies, especially pancreatic cancer. Furtherinvestigation of the capability for induction of RAB6KIFL-specific CTLsin pancreatic cancer patients thus remains an issue of great importancefor clinical application.

INDUSTRIAL APPLICABILITY

The present invention describes new TAAs, particularly those derivedfrom RAB6KIFL that induce potent and specific anti-tumor immuneresponses and have applicability to a wide array of cancer types. SuchTAAs warrant further development as peptide vaccines against diseasesassociated with RAB6KIFL, e.g., cancers such as bladder cancer, cervicalcancer, cholangiocellular carcinoma, esophagus cancer, gastric cancer,non-small cell lung cancer (NSCLC), osteosarcoma, pancreatic cancer,renal carcinoma and soft tissue tumor.

While the present invention is herein described in detail and withreference to specific embodiments thereof, it is to be understood thatthe foregoing description is exemplary and explanatory in nature and isintended to illustrate the invention and its preferred embodiments.Through routine experimentation, one skilled in the art will readilyrecognize that various changes and modifications can be made thereinwithout departing from the spirit and scope of the invention, the metesand bounds of which are defined by the appended claims.

The invention claimed is:
 1. An isolated oligopeptide, wherein theoligopeptide consists of an amino acid sequence selected from the groupconsisting of SEQ ID NOs: 3, 4 and 5 in which 1 or 2 amino acids aresubstituted, wherein the substitution is selected from the groupconsisting of: (a) the second amino acid from the N-terminus issubstituted with leucine or methionine and (b) the C-terminal amino acidis substituted with leucine, wherein the oligopeptide has cytotoxic Tlymphocyte (CTL) inducibility.
 2. A pharmaceutical composition fortreating cancer, wherein the composition comprises a pharmaceuticallyacceptable carrier and one or more oligopeptides consisting of the aminoacid sequence of SEQ ID NO: 3, 4, or 5, or one or more oligopeptides ofclaim 1, wherein the pharmaceutically acceptable carrier is sterilizedwater, physiological saline, or phosphate buffer.
 3. The pharmaceuticalcomposition of claim 2, which is formulated for the administration to asubject whose HLA antigen is HLA-A2.
 4. The pharmaceutical compositionof claim 2, wherein the cancer is selected from the group consisting ofbladder cancer, breast cancer, cholangiocellular carcinoma, esophagealcancer, non-small cell lung cancer (NSCLC), pancreatic cancer, prostatecancer, renal carcinoma and small cell lung cancer (SCLC).
 5. Apharmaceutical composition for inducing a CTL, wherein the compositioncomprises a pharmaceutically acceptable carrier and one or moreoligopeptides consisting of the amino acid sequence of SEQ ID NO: 3, 4,or 5, or one or more oligopeptides of claim 1, wherein thepharmaceutically acceptable carrier is sterilized water, physiologicalsaline, or phosphate buffer.